The scope guard protects your rifle scope from external weather influences and scratches. The scope guard can be removed quietly, even when wearing gloves. Size S fits all rifle scopes with an objective lens diameter of 20mm and 24 mm. Size M fits all rifle scopes with an objective lens diameter of 42 mm. Size L fits all Z8i(+), Z6i, Z4i, Z5 and Z3 rifle scopes with an objective lens diameter of between 44 and 56 mm. Size XL fits all dS and X5(i) rifle scopes.