Had to bore the nose of my Model 660 Surefire to 0.852" to 0.600" deep in order to seat the P60 LED replacement. Fortunately I have the machine tool capability to do that.
Replacement now works fine as does the original incandescent lamp.
Perfect Surefire G2 Replacement
I replaced the bulb in my G2 Surefire with this one and am so happy with the light output. Really bright - as the other reviewer stated just remove the spring from the outside of bulb and it drops right in. Great Value
This works great for my G2 Nitrolon. Upgraded from the original (non-LED, battery-eating) bulb that came with the G2. The only issue I had was that as-shipped, it did not fit in the flashlight. I called Gary at GG, and he explained that I needed to remove the outer spring for this application - now works great! It's super-bright, and I saved quited a bit of $$ vs. the OEM upgrade, which sells for $49.