This is a factory Smith & Wesson SD40 10-round magazine, chambered in .40 S&W. This also fits SD40VE models.

Smith & Wesson delivers unmatched superiority, adding confidence to every shooting experience with magazines that are built with precision and unrivaled craftsmanship. This factory 10 round magazine features a silvered steel construction, with a hi-tensile spring and black polymer follower for a reliable feed when firing. Witness holes on each side of the magazine allows you to see how many rounds you have loaded in. These updated magazines for the SD40 are also compatible with the SD40VE.

It’s equipped with a removable floorplate for easy cleaning and its polymer follower helps to ensure reliable feeding. The magazine also has an anti-tilt follower and an ergonomic baseplate for reliable feeding and removal from the pistol.