I have two Surefire G2's and an older Dorcy dual cell lights. All had the incandescent stock bulbs. I've always run Surefire, energizer and Duracell batteries. Until a found what I thought was a great deal on two rechargeables and charger, But come to find out there are two different offerings in the 123's. Protected and unprotected. These were unprotected. Therefore they can actually be charged over 3.0 volts. I put the fully charged batteries in a g2, it came on super bright, then the bulb failed. Figured it was a fluke, but it did the same thing to my second g2. However it did not harm my Dorcy. I measured voltage at the battery, 3.7 volts. So 7.4 volts on a 6 volt lamp. The stock Surefire g2 lamp is a 6 volt lamp. The dorcy is a variable voltage lamp. SO, I decided to try the Surefire 120 lumen LED replacement cap. Typical white LED beam, but poor throw. I think the 60 lumen incandescent has the same throw. But it boasted a 9hr battery life. Ultimately I was dissatisfied, and returned the led cap. Popped onto eBay and located a Cree R5 lamp assembly, from china, for $12.91. It's a 6-18 volt lamp, so the rechargeable batteries won't flash kill them. Light intensity and throw is far superior to the Surefire LED. states a Max 380 lumen output at 18 volts. Ultimately, I'm pleased with the Chinese lamp, and will definitely be ordering back ups.