The Butler Creek Element Scope Caps are highly rugged with a multi-flex sleeve. The objective flip out printable dope disk provides wind and elevation information. Create a watertight, airtight seal lens cover you can open with a touch of a button so you can put your shot through the narrow window of opportunity in the most extreme conditions. 1.38-1.58" (35-40mm) Model ESC40 180 & 270 degree lip open positions Interchangeable disk inserts for changing environments Stainless steel hardware Strong polymer material to withstand punishment Multi-fit design with 10 total caps in line to fit 95% of scopes on the market