Did you purchase an HK416/MR556 and find the hand guard to be… lacking? The Maxim Defense HK416/MR556 Handguard is your salvation. They are machined from 6061 aluminum, hard coat anodized for increased wear and corrosion resistance, and feature M-Slots on five sides. All lengths and styles feature QD mounts on each side for low profile sling mounting. These hand guards are only compatible with Maxim Defense PDX/MDX receivers and those with HK MR556 mounting styles.