September, 2014

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K40 Laser Defuser g5 laser jammer – Review




Since 2010, our forum has discussed the performance of K40 products, such as their radar detectors and their laser jammers.  As time progressed, only a few members in the community discussed their experiences with their K40 products.  The three main reasons why there have been scattered reviews about these products is due mainly to the exclusive marketing approach, cost, and available purchasing avenues which results in a small population of owners.  A common response shared by a few of these members regarding their experiences with their K40 detectors and jammers has centered on disappointment due to the performance of the product with respect to the cost of the system.  In comparison to more popular radar detectors and laser jammers, the performance of these systems has simply not impressed users.  Finally, after almost four years, we finally had a member, who owned a new K40 Laser Defuser g5 laser jammer, and allowed us the opportunity to test it so that the community could see true metrics of this product’s performance against popular laser guns.


Product Information – K40 Laser Defuser g5 laser jammer

    • Cost: $399.95 (online at Amazon); Authorized Installer cost is higher.
    • Components included in kit:
      • 1 (ea.) Laser Defuser g5 transponder unit
      • 1 (ea.) License plate mounting frame
      • 1 (ea.) Universal mounting frame (holds the transponder and allows for mounting on various parts of the vehicle)
      • 1 (ea.) Bag of installation screws/nuts, and crimp-connectors
      • 1 (ea.) Sync Interface (CPU module that accepts four transponders, and has a built-in speaker for alerts)
K40 Laser Defuser g5 laser jammer
    • Transponder Specifications:
      • Reception: Five (5) IR diode receivers
      • Transmission: Ten (10) LED diodes @ 904nm
      • Lens: “Fly-Eye Lens” for increasing reception to off-axis LIDAR sources
      • Dimensions (L x W x H): 5.1″ x 0.89″ x 0.694″
    • CPU (“Sync Interface”) Specifications:
      • Power requirement: 12.0+ volts (DC)
      • Transponder ports: Four (4)
      • Dimensions (L x W x H): 3.1″ x 1.0″ x 1.75″
    • Operating Modes:
      • Constant Transmit – transponder continuously counters the threat during the laser encounter (user must manually deactivate the system to stop it from firing)
      • Pulse Transmit – transponder will emit a jamming signal for five (5) seconds before stopping automatically and rearming itself after 30 seconds (this allows the driver to safely slow down to the posted speed limit and allow the laser gun to get a reading after a five seconds)
      • Receive Only – transponder will only alert the driver to the presence of a LIDAR source and not emit any counter signals


Comparison With Other Laser Jammers

Key Comparison Factors
K40 Laser Defuser g5 AntiLaser Priority (ALP) Blinder HP-905 Laser Interceptor
Price for base system *$399.95 (1 sensor/1 CPU)
*online price
$499.95 (1 sensor/1 CPU) $599.00 (2 sensors/1 CPU) $699.00 (2 sensors/ 1 CPU)
Cost for Additional Sensors $350-$390 $249.95 $199.97 $250.00
Ports for Additional Sensors 4 5 4 4
Ability to Receive Updates No Yes Yes Yes
Diode type LED Laser Diode Laser Diode Laser Diode
Smartphone App Compatible No Yes (Apple iOS) No Yes (Android)
Protection Against Variable Pulse Rate (VPR) LIDAR None – Poor Great Good Good


K40 Laser Defuser g5 – Technical Overview

While there are no doubts we had if the K40 Laser Defuser g5 emitted signals to counter LIDAR guns, we took this opportunity to take a close look at the signal output of the system.  Although a transponder from any system can output a signal, we wanted to see if the signal coming from the g5 Defuser was some random noise or if there was a distinct pattern in the signal to counter the series of pulses from a known LIDAR gun.  For the purpose of this test, we used a very common laser gun known as the Kustom ProLaser III (PL III).  The known pulse rate of this LIDAR gun is 200 pulses per second (pps).  In the video below, we use an oscilloscope to display the infrared (IR) signals emitted from the LIDAR gun and the counter pulse patterns from the K40 Laser Defuser g5.  We were able to capture the pulse patterns from the K40 g5 by simply targeting the transponder with the PL III gun and then recording the pulse patterns on the oscilloscope.

Findings from oscilloscope testing:  Our initial thoughts on the legitimacy of the counter pulse patterns were proven correctly – the K40 Laser Defuser g5 does emit pulse patterns that clearly mimic the pulse trains of the known LIDAR source, and does not emit a random pulse pattern.  This is important because there may have been some members or prospective customers who were skeptical that the K40 possibly produced some blanket-type of jamming signal, consisting of noise, which would result in poor performance.  Such practices do exist, as we discovered in a prior test against the validity of the Rocky Mountain Radar C495.


K40 Laser Defuser g5 – Road Test

Testing Conditions and Equipment

Our key tester for the K40 Laser Defuser g5 laser jammer (single transponder) system, Vortex, installed the system on a test vehicle as shown below.  The installation method was the same one followed by a K40 authorized installer, which involved installing the transponder on the most forward and center part of the vehicle.  In this case, Vortex installed the transponder on the license plate, ensuring it was pointed straight ahead and level to the ground.

K40 Laser Defuser g5 - Front Installation Single Transponder

K40 Laser Defuser g5 – Front Installation Single Transponder

 Testing Conditions


  • Vehicle: Mazda Miata
  • Test Course: 1000′ (straight, business road)
  • Weather: Clear and Sunny
  • Vehicle Speed: ~30mph
  • Testing LIDAR Guns:
    • Kustom ProLaser III
    • Laser Technologies Ultralyte 20/20 LRB
    • Applied Concepts Stalker (2 versions)
  • Other Members Witnessing: Hahns52, Filibuster, stlth_amg


K40 Laser Defuser g5 – Testing Results

The following test demonstrated how a K40 Laser Defuser g5 laser jammer (single transponder) would perform on a small sports car like this Mazda Miata.  During this test, the test vehicle travelled toward the LIDAR operator from approximately 1000 feet away at a speed of 30 mph.  The LIDAR operator of the Kustom ProLaser III targeted the vehicle three independent times on three locations on the vehicle (Left Passenger Bumper Area (LH), Center Mass (CM), and Right Passenger Bumper Area (RH)).

k40 test results

Results Summary:  The test results were better than we expected, however, overall, the results were not supportive to garner our recommendation as an alternative to any of the current big three laser jammers.  When the vehicle was targeted at Center Mass (CM), the K40 Laser Defuser g5 had excellent results against the four LIDAR guns.  Against targeting on the sides of the vehicle, the K40 g5 laser jammer had mixed results.  Unlike results for systems like the AntiLaser Priority (ALP) or Laser Interceptor (LI) where measurements from side shots occasionally happen, the measurements from this test were taken from at least 500 feet away from the LIDAR gun operator.  This performance is less than average, and given the most optimal conditions in terms of weather and installation, such encounters in a real world scenario would most likely result in a speeding ticket.  When tested against the Stalker LIDAR gun version 5.8, the K40 g5 had great results and the LIDAR operator was not able to acquire readings.  Testing against variable pulse rate (VPR) LIDAR guns, such as the Digital Ally Laser Ally (DALA) or Dragon Eye Technologies Compact (DET), has shown that the system will alert to these LIDAR guns, but will not counter them.  This lack of protection from VPR sources and the hit-or-miss performance against some of the most popular LIDAR guns currently used by law enforcement agencies is what leads us to rate this product as non-favorable.



Overall, we were excited to finally test a K40 Laser Defuser g5 system and provide answers to critics or support for the K40 customers.  Testing these elusive products has been very challenging for the staff because very few people own K40 systems, and the people who do own them or have owned them in the past, do not discuss them often enough on the forum.  This has resulted in very little feedback which has mostly centered around poor performance and difficult to validate.  Most members would agree that the K40 “works,” but working and performing in real world scenarios are two ideas spread greatly apart.  In our testing, we showed that the K40 Laser Defuser g5 laser jammer works but performs poorly.  As a forum that does not sell or sponsor products, we have no reason to fluff or negatively discount product results.  Places like have made false claims about the K40 Laser Defuser g5 because they support the company and as a result, make videos and commentary portraying the strength of these systems.  This seemingly positive feedback is what confuses buyers because they are not aware of other factors affecting the performance of a product, and then see true real-world testing results from independent sources like us.  As an example, in a video made by, the commentator states that no laser jammer is capable of countering VPR LIDAR guns, yet, the AntiLaser Priority (ALP) currently defeats this LIDAR gun, as seen in this video.  Although the K40 Laser Defuser g5 can detect VPR LIDAR sources, this fact is moot since detection is not the same as jamming.

In our testing, the K40 had mixed results in terms of jamming four of the most popular LIDAR guns currently used on highways.  These results were obtained given optimal conditions with respect to installation, weather, and environmental factors.  On the positive side, when the vehicle was targeted at center mass, the K40 Laser Defuser g5 was a great performer.  The K40 g5 laser jammer did not do so well when the vehicle was targeted on the sides.  With certain speed readings taken from at least 500 feet away, we were not satisfied.  Despite these mixed results, is it possible the results could have been improved?  Absolutely.  This test vehicle only had one (1) sensor mounted in the center.  Although the manufacturer stands behind the use of one sensor for protection, based on our independent testing of many systems, two heads are better than one.  With two transponders, there is more protection available to a vehicle to counter side shots, which was the problematic area with this setup.

Some people might ask if we would recommend this system if it was a dual setup (two transponders).  Our answer would still be, “No.”  Adding another transponder would add approximately $380 to the original price of a base system resulting in a total cost of at least $780.00.  This puts the cost of the system well above the cost of any other laser jammers.  Besides cost, the top three laser jammers have much better performance in terms of stronger power from laser diodes, and firmware support to counter new LIDAR guns and firmware changes in current LIDAR guns.  Additionally, some of these systems support apps for smartphones, like the ALPConnect and the Laser Interceptor Bluetooth Adapter.  Lastly, certain systems are capable of utilizing one transponder, like the AntiLaser Priority (ALP), and perform much better than the K40 Laser Defuser g5 as seen in this video:



For further discussion of this test, please refer to the following link:

We would like to thank our member “SadisticPatrons” for providing our forum the K40 Laser Defuser g5 laser jammer to test.  Thanks also go out to our veteran member and longtime tester “Vortex,” and our loyal members “Hahns52,” “Filibuster,” and “stlth_amg” for providing assistance during the testing and support for this hobby.