ZEV TechnologiesPRO Magwell 1st-4th Gen GlockA(R) Aluminum 1 piece design finished in a black smooth Anodized includes magwell, screw and wrench. The magwell is slightly flared at the base to be wider than the stock opening, which is ideal for quickly inserting the magazine in the pistol during reloads helping build proper muscle memory for improved consistency and reload time. This ZEV TechnologiesPRO Magwell is a great addition for any shooter looking for an edge with out the bulk flared competition style magwell. The addition of a magwell will help keep the users hand in place while shooting. Generation 4 back straps may need to be modified if used with this Mfg: Zev Technologies