The Sentry™ Refrigerant Locking Caps are quick and easy way to comply with the IRC and IMC codes requirement that all outdoor access ports on A/C and refrigerant equipment have to be tamper resistant. This cap is anodized in red color for easy identification of R-410 refrigerant. It is designed for 1/4 in access ports. An O-ring seal is also pre-installed to prevent leaks.