This U.S.A made ProMag Glock 42 magazine is constructed of a proprietary Dupont Zytel derived high impact polymer, with a steel insert for added rigidity to the feed lips. The result is quality, reliability, and consistency. 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.