"Std Two Piece Base Mtt USRE WSSM Description For maximum accessibility to the magazine or breech area of your rifle, STD 2-Piece Bases are worth a look. Fluted for a ""custom"" look, these bases are also ideal if you're after greater flexibility when it comes to mounting options for your bolt action rifle. Reversible bases are available for many actions, accommodating a variety of scopes and action lengths. Additionally, STD 2-Piece Bases fit right-hand and left-hand actions. Long Range STD mounts provide 1/4 degree of built-in elevation. "