its a simple 3x10 magnetic strip, advertised to attach inside a gun safe to hold/store metal mags. advertised weight limit 3 pounds. well unfortunately the magnet material is not strong enough to hold full mags. at least not very well. if you place them gently they will stay, but a slight bump or jar and they fall off. I mounted mine on the underside of the top shelf in my safe. carefully placed the mags, 3 loaded 1911 mags, 2 loaded SR9 mags (17 each) and 2 loaded M&P 45 mags, (1) 10 round and (1) extended 13 round. i closed the door to check clearance, opened it, and gave the shelf a light fist thump from the top. all 7 fell instantly.