The Cap Keeper Plus Lens Cap Holder from Sensei prevents the loss of lens caps. An adhesive-backed disc secures the lens cap to the elastic leash which wraps around the lens barrel. With the lens cap removed from the lens while shooting, it hangs out of the way but secure and within reach for easy retrieval. The Cap Keeper Plus is made with tough and extremely secure elastic.
purchased this to use with a lens cap for a swarovski SLT spotting scope. Upon researching this tether, there were concerns that the adhesive used to keep the cap hold attached to the lens cap did not last very long. I ended up cutting the adhesive disc off and attaching the lens cap holder to the lens cap by running the string through a 3/32" hole drilled through the lens cover release tab and securing with a knot and a drop of super glue gel on the knot. Works fine so I dont have to worry of easily losing another lens cover .
I've been using one of these for a few years, and finally stocked up on a few more for my other lenses. Good price, looks nice, and keeps my caps safe from forgetfulness!