Pachmayr Mag Sleeves adapt full-size magazines for use with compact handguns like the Glock 20 and 21 magazines to fit the Glock 29 and 30 model. Mag Sleeves allow you greater shooting capability by increasing the gun's grip size and capacity with additional rounds. Carry your compact pistol with a standard magazine when concealment is important, or insert a high capacity magazine fitted with your Pachmayr Mag Sleeve when the situation calls for it. Their Mag Sleeves simply slide over the magazine and fit securely in place via a set screw. Improve your handling and performance of compact handguns. DISCLAIMER: This product is not manufactured, authorized, endorsed, or warranted by GLOCK. GLOCK does not warrant or represent that this product is compatible with GLOCK pistols.