The Perfect Zero 1911 Double Stack Magazines are made with the same tube, spring, and follower as the Atlas Gunworks Classic and Premium Magazines. The only differences are the polymer base pad and PZ laser engraving. They are available in 17 and 20-round configurations. We recommend Perfect Zero magazines to shooters looking for an economical magazine that feeds awesome and locks back reliably in most modular 1911 double stack and 2011 style pistols, including Staccato* and Springfield Prodigy. Description Features: Caliber: 9mm Capacity: 20 rounds Tube: 140mm Stainless Steel Follower: Lockback Spring: + 18% Basepad: Polymer Backed by the Atlas Magazine Warranty Compatibility: All Atlas Gunworks Pistols All known 2011 style and 1911 double stack modular pistols Staccato*: Staccato C2, Staccato P, Staccato XL, Staccato XC using a Staccato Magwell Springfield: Prodigy 5" 1911 DS, Prodigy 4.24" 1911 DS