Quick view Leupold Leupold 50234 Standard Base Matte Black Cooper Arms 16/22/23 $27.27 $22.99 Leupold steel Standard (STD) rings and bases are the most versatile of any mounting system we offer. This specific model fits a Cooper 22/16/23 and is the perfect choice for standard calibers less than .300 Win. Mag. STD rings come in five different... Compare Add to Cart