MDT Detachable box magazines are designed to fit the MDT TAC21 and LSS Chassis systems, as well as many other M24 type chassis and bottom metals. Manufactured from high quality Polymer and uses a tempered steel spring. These magazines were put through vigorous testing. They're made from high quality strength polymer with a high glass content to ensure durability and strength. Although not unbreakable, they have been driven over with cars and trucks which did not break them.