Caliber availability: 9mm, .40 S&W, .357 SIG; Upgraded, high-cut 1911-style beavertail grip tang for smooth draws; Undercut front-strap and reshaped, radiused trigger guard for the highest grip possible; Enlarged, integrated magwell opening for fast reloads-compatible with the latest generation Sig Sauer X-series factory basepads; Improved grip traction and increased grip pattern coverage with Wilson Combat's exclusive Starburst grip pattern on the sides and aggressive texturing on the front and backstrap; Frame reference serrations for support hand thumb or index finger positioning; Internal Slots for Rod-style Tungsten Weights; Angled "Holster Cuts" on light rail to aid in snag-free, re-holstering; Factory Sig Sauer magazine release pre-installed; Compatible with all standard holsters and all current production, X-Series basepads