Sold by the foot or multiples there-of.

Simply cut it to the length needed and insert it into the hollow double jointed cocking levers like on the R7-HW30, R6, Hw50's-55 etc.

Install the split ends into the lever first. Most often if pressed in it fits well but can be sanded, buffed or ground for a perfect fit. Does not need glued in. Eliminates receiver galling prominent in these guns. Be careful not to over grind it as it will compress in the lever with minor effort. You want it about 10 thou higher than the lever. On newer guns that have deeper levers you can shim up the insert, double it face to face and many use a small portion and fit in the cocking lever like the factory roller etc. Many ways to use these.