The lezyne femto drive duo is a bit of a best of both worlds sort of light incorporating both front and rear lights the femto duo is a two in one safety light integrated into a versatile helmet mount evolved from the popular femto series the unit features a front and rear light coupled by a composite matrix junction thats compatible with nearly all vented style helmets the leds are housed in a super compact lightweight and durable machined aluminum body and the high grade polycarbonate