This is the ATI Bulldog 410 gauge 10 round magazine.

Crafted from heat-treated steel with an anti-tilt polymer flower, plus flared feed lips for smooth, dependable feeding, this lightweight magazine is easy to handle and perfect for quick deployment. Its compact profile offers a snag-free design for easier storage and enhanced maneuverability in tight spaces. With a 5-round capacity, this magazine is ideal for home defense, the range, or hunting (where legal). Designed for a seamless fit with the ATI Bulldog .410 gauge, it delivers reliability without the bulk.