This Schmidt & Bender 42mm Sun Shade fits their riflescopes that have a 42mm objective lens. A sun shade is a necessary accessory for every user of a riflescope, and should definitely be a part of your sighting system. These sun shades help to eliminate or reduce flare, glare & reflections. By blocking unwanted stray light from oblique light sources that would otherwise enter the light path of your scope, your sight picture will remain intact and uncompromised. This is a rugged black aluminum shade that is threaded to fit directly onto the front of every Schmidt & Bender riflescope with a 42mm objective lens.