This is a factory Shadow Systems CR920 9mm 13-round extended magazine.

Features:

• Durable steel body
• Anti-tilt high visibility orange polymer follower
• Rear-facing numbered round indicators
• Polymer base pad

Here is more info on the CR920 pistol:

The CR920 is an ultra-concealable subcompact that is designed with comfortable shootability in mind. Designed to shoot like a full size pistol, the CR920 conceals easily inside G43X MOS or G48 MOS holsters, while packing a 13+1 round extended capacity or 10+1 flush-fit capacity.

The CR920 comes equipped with the Shadow Systems features you have come to expect, like an aggressively textured frame. The frame texture is wrapped around the frame to keep the CR920 firmly seated in the shooter’s hands, despite its small size. The extended magazine baseplate features the same texture on the front, to allow an extra tacky point of contact for the pinky finger.