I've been looking to get an "AA" model to replace my Fenix TK10. Looking around online I was liking the Fenix LD25. I stopped in a store to get some 5.11 pants and they had Fenix lights, so I got to check it out. I really liked the feel of it and got to play with a display model. I grabbed one. Getting it home and fiddling with it, I like it! I am impressed with the brightness and the use of AA batteries is a gigantic bonus. The default "outdoor mode" is 180 lumen (1hr46min runtime) and 45 lumen (13hr runtime). The "hidden" modes are a 85 lumen(6hr15min RT) /3 lumen (74hr RT) "camping mode" and a 85 lumen/ 45 lumen SOS flashing "Rescuing mode." You switch between the A/B outputs by loosening/tightening the head. You switch modes by quickly turning the head tight/loose X 2. The light will stay in the chosen mode until you change it. The body has been overmolded with plastic, giving it a nice feel and grip. Left, TK10 @ 60 lumens right, LD25 @ 45 lumens Here, you can see the difference of the "Neutral white" LED of the LD25 vs the TK10. It almost looks like the light from an incandescent bulb, but it's very uniform as LED lights are. Left, TK10 @ 225 lumens right, LD25 @ 180 lumens =============== Features of Fenix LD25: • Cree XP-G Neutral White LED (R4) with a lifespan of 50,000 hours • Two modes of output - High (180 lumens, 1h46min) -> Low (45 lumens 13hrs) • Uses two 1.5V AA (Ni-MH, Alkaline) batteries • Dimensions • Length: 164mm / 6.46in • Diameter: 25.4mm / 1.00in • Weight: 75.5grams / 2.7oz (excluding batteries) • Digitally regulated output - maintains constant brightness • Patented physical structure avoid circuit damaging from reverse connection of battery • Anti-slip and anti-freezing plastic grip can be used under adverse weather conditions • Tactical push-button tail cap switch • Made of durable aircraft-grade aluminum • Premium Type III hard-anodized anti-abrasive finish • Toughened ultra-clear double glass lens with anti-reflective coating Notice: The above-mentioned parameters (tested by 2500mAh Ni-MH battery in Lab) are approximate and may vary between flashlights, batteries, and environments.