Those are Rimfire Scopes.

Want one that's durable & cheap... under $100???.....
..... then Click Right Here

You can cover scope-bottoms with lots of things using scissors. Also... most of the mess on scope bottoms is sometimes only primer residue... which is non-corrosive. You can also purchase T/C scope covers for MLs at many hunting stores... even at Bass Pro where I found the scope for you. Just click on 'scope accessories' there to find it.