This is a Pro Mag drum magazine, designed to be perfectly compatible with your Glock 42. It is meticulously built using DuPont Zytel Polymer accompanied by a full-length steel internal insert for ensured durability and reliability. Featuring an injection-molded mag follower and a mag spring formed from chrome silicone wire, the construction of this product is robust and built to last. Proudly made in the USA, this Pro Mag drum magazine is an assurance of quality and high performance.