Daniel Defense Castle Nut. These AR15 Lower Parts by Daniel Defense are finely crafted with recesses for staking your rear receiver end plate to prevent the castle nut from coming loose. Featuring a heavy magnesium phosphate coating the Daniel Defense Securing Castle Nut is also compatible with common armorers and castle nut wrenches. The Daniel Defense Castle Nut Ring is a sturdy and affordable way for you to secure your receiver extension to ensure maximum durability. Specifications for Daniel Defense Castle Nut: Manufacturer: Daniel Defense Gun Model: AR-15 Condition: New Package Contents: Daniel Defense Castle Nut DDD-CAN-CSTNT Daniel Defense Warranty: Guaranteed Satisfaction All Daniel Defense products carry a 100percent satisfaction guarantee against defects in original materials and workmanship. If your Daniel Defense product shows evidence of such defects Daniel Defense will make every accommodation to fix repair or replace your product in the most expeditious manner possible. Daniel Defense does not warranty products or damage caused to our products by the correct or incorrect installation of other manufacturer's products. Warranty information and warranties are supplied solely by the manufacturer and not this retailer. This retailer publishes information from the manufacturer for information purposes only and the manufacturer is solely responsible and liable for any warranty information and warranties published by this retailer. Please reference the appropriate manufacturer documents or reach out to the manufacturer directly for full warranty terms and effective dates. What firearm models does the manufacturer say Daniel Defense Castle Nut is compatible with? The manufacturer suggests that Daniel Defense Castle Nut is compatible with AR-15Daniel Defense 15-057-20039: Castle Nut