Product Description The Yankee Hill Machine Co caliber marked dust cover assembly is a practical upgrade for AR-platform rifles, helping clearly identify your upper receiver&';s chambering at a glance. Marked "300 BLK," this ejection port cover is ideal for shooters who run multiple uppers or change calibers and want fast, unmistakable visual confirmation. The assembly includes the caliber-marked dust cover plus the necessary hardware for installation. Product Highlights Caliber-marked "300 BLK" dust cover helps prevent caliber confusion when swapping uppers Complete assembly includes dust cover, rod and retaining clip, and spring Designed to fit AR-platform rifles Durable black finish to match common AR receiver aesthetics Simple, functional replacement or upgrade for standard ejection port covers Specs Brand: Yankee Hill Machine Co Product Type: Caliber marked dust cover (ejection port cover) assembly Caliber Marking: 300 Blackout (300 BLK) Compatibility: AR platform Color: Black Included Components: Caliber marked dust cover, rod and retaining clip, spring Manufacturer Part Number: YHM-111-300 UPC: 816701017717 Disclaimer: We strive to provide accurate and up-to-date product descriptions, specifications, and images; however, errors or omissions may occasionally occur. We are not responsible for any inaccuracies or discrepancies in the content provided. If you notice anything incorrect or unclear, please contact us so we can correct it. When in doubt, we recommend verifying details directly with the product&';s manufacturer.