Magpul Maglink Coupler for 30/40 RD PMAG 

• Compatible with 30/40 RD PMAG AR/M4
• Allow the User to Attach Two Magazines Together
• Increases Efficiency with Speed Reloading
• Keeps Additional Ammo Accessible on the Weapon
• Two Piece Design
• Durable and Lightweight Polymer Construction
• Made in the USA