Here's a great idea for the AR-15 owner who uses multiple uppers on the
same lower receiver or identically configured rifles in different
calibers. Just add a caliber-marked dust cover to your modern sporting
rifle and tell them apart at a glance! These dust covers include the
rod, retaining clip and spring and fit all standard AR upper receivers.
Features and Specifications:
Manufacturer Number: YHM-111-556
Complete dust cover assembly
Caliber marked "5.56 NATO"