Back when the Fenix L2D was my main light I used the optional strap that came with it. It went through the tailcap and got wrapped up by the velcro strap that held the light in place, and I figured it would make it harder to loose the entire light if it came out the holder or the cap when I was changing batteries. Extra insurance that I don't think I ever needed, but it was reassuring when I was changing batteries under the streetlight.