Bought this to replace the stock box mag that comes with the Classic Army Knights Armament Stoner 96 - Fits perfectly, just need to swap out the M249 specific Bowden tube attachment for the one that came with the Stoner. Haven’t fielded it yet, but initial tests in the back yard show improved and more reliable feeding. The increase in capacity is a nice benefit too. Only knock I’d give this magazine is, the port/window for loading BBs is very small and not super secure. Granted, it’s under the canvas covering of the mag, so it shouldn’t open and spill any BBs. Nice upgrade to the stock Classic Army mag.