I also own the original E15. This model is identical in looks but has a higher output. I am very satisfied with it and it is ideal for fitting to a key ring.
A great torch, very bright with four settings, well engineered, rugged but small enough to fit on a key ring.
I'm very pleased with this and would definitely recommend,
In case you don't know the name, Fenix are at the leading edge of LED torch design and are one of the most reliable manufacturers. I have several models and none of them have failed. I did foolishly damage the switch on one of them; Fenix sent me a new one free even though it was my fault.
This tiny little E15 weighs next to nothing yet is as bright as a car headlight used to be. The max 450 lumens doesn't last terribly long but you rarely need a torch that bright. Even on 'medium' it is plenty bright enough for use as a bike light and 'low' is plenty for walking with.
I really can't imagine anyone being disappointed with it. It will even take rechargeable batteries - so running it is virtually free too.