This Leupold Standard 2 Piece scope Mount Base (50031) gives you maximum accessibility to the magazine or breech of your rifle, and more flexibility in mounting scope to bolt action rifles. Leupold STD 2-piece base is worth a look. Fluted for a "custom" look, it's also ideal if you're after greater flexibility when it comes to mounting options for your bolt action rifle. Reversible base is available for many actions, accommodating a variety of scope and action lengths. Additionally, STD 2 Piece base from Leupold fit right-hand and left-hand action.