Butler Creek Scope Cap 30-40MM

Fast, flip-open design;
Custom fit for most scopes,
Water-tight,
Custom-fit friction mounts anchors them to your scope,
Air-tight semi-O-ring keeps out dust and moisture,
Measure the outside diameter of their scope tube to get the proper fit,
Instant action lids pop open at the touch of a thumb,
Weighs less than an ounce