The Tracker Safe PPM4 is a must have safe accessory. It can hold 4 pistol magazines and can be placed anywhere there is carpet; i.e. back of safe doors, inside walls of safes, cars, trucks, etc. Keep your pistol magazines ready and organized with the Tracker Safe PPM4. The PPM4 pocket is constructed of strong durable nylon fabric on the front and the back is fully covered in Velcro. In the center is a thick plastic core that gives the PPM4 its rigidity. The individual pistol magazine holders are made with nylon fronts and thick elastic sides that hold the magazines firmly in place. The elastic stretches to fit most pistol magazines on the market. Please test your safe's carpet for compatibility with Velcro.