This is the SAR USA SAR9 Compact 9mm 10-round magazine.

Welcome to the most durable and reliable California compliant magazine for your SAR9 Compact! 

Constructed from high-quality steel and featuring an impact-resistant polymer floor plate, this factory magazine is designed to withstand serious use. And keeping it running reliably is an anti-tilt polymer follower and high-tensile steel wire spring. 

You may be limited in how many rounds are in each magazine, but not with how many magazines you can purchase!  

At only ten rounds a piece, you might as well order a few!