Approx. 18 months, 3500 miles of commuting and weekend rides and my DX P7 5-mode is still working fine. I run high mode in the dark and fast strobe during daylight. It requires 2 button magnets on the back of the battery to prevent mode changes when going over bumps. I've had some problems with the 18650 batteries, though. Of the 6 gray ones I ordered with the light, two are totally dead now. I ordered 6 blue ones about 3 months ago and 2 of them seem to discharge twice as fast as the others - I'm guessing they aren't able to take a full charge. But for the price and performance, it's been a great product.