This is a Smith and Wesson M&P 15-22 .22 LR 10-round short magazine.

This factory M&P 15-22 magazine features lightweight polymer construction for superior strength and lasting durability in virtually any environment, and large windows allow you to easily see your remaining round count at a glance.  The heat-treated steel spring and durable polymer follower ensure smooth, reliable feeding in high-stress situations.  Further, the compact size makes these 10-round mags perfect for shooting prone or from a bench.

These M&P 15-22 10-round magazines incorporate recognizable AR-15 features, trademark S&W craftsmanship, impressive performance, and fit and function that’s hard to match.