Ok, so I inherited a DPMS Ar15 that came with an EagleEye Optics CO red dot scope. There is no model number on the scope and I found that EagleEye was a dubious company that went under. The scope so far is pretty nice, no gripes on it. It came with some Butler Creek flip up lens covers and the front cover broke. The only markings on it were L20 EYE. Went to find a replacement and it asks for the outside diameter. Can I get just a size 20? I was guessing the L stood for left as that is the side the open lever is on.