Review on Super Bright Yellow Light Led Replacement Bulb Single Mode P60 LED Drop-In Module Design For Surefire Hugsby C2 G2 Z2 6P 9P G3 S3 D2 Ultrafire 501B 502B And Other Hunting Flashlights by Andrew Mack

Picked up both the 850 and 940nm IR versions, using them in my old Surefire G2 bodies. As mentioned by others, the spring is too big and should be pulled off. It still barely fits, but the shell makes contact with the battery sleeve and it works. One unit was DOA but was replaced quickly. To the naked eye, the 850nm has a red glow, 940 is barely noticeable. Through a Gen 3 PVS-14, the 940 would make a good navigational light - it's visible, but it doesn't have a huge throw. The 850 is VERY bright, and causes the gain to cut back. Great for longer distances or breaking through a photonic barrier. I'm waiting on a Surefire IR filter to compare to the OEM bulb. Had these just a few days so I can't say much on durability yet. Each one may not be a perfect light, but both are good tools for their purpose, and at a good price compared to high end dedicated IR illuminators.