The SharkBite UA23102A25 expansion sleeve is a 1/2-inch, white plastic ring designed specifically for use with PEX-A piping systems. It comes as a 25-pack, giving you multiple sleeves in one purchase so you'll have extras for larger plumbing jobs or future repairs. The sleeve is made from injection-molded PEX plastic and features an interior cross-hatch structure that prevents the sleeve from sliding off the pipe once installed. A chamfered edge and an internal "stop" help guide and position the sleeve correctly, making installation easier and reducing the risk of misalignment. When paired with the proper PEX expansion tool and expansion fittings, the connection becomes secure - designed to grow stronger over time rather than weaken - which helps ensure leak-free performance over the lifespan of the plumbing system. Because it's built for PEX-A pipe and fittings compliant with industry standards, it is suitable for potable water, radiant-heating, water-service lines, and even direct-burial applications (including encasement in concrete). The sleeve supports a useful range of working pressures and temperatures (for example, up to 160 psi at room temperature, or up to 80 psi at 200 deg. F), making it versatile for hot- and cold-water plumbing or hydronic heating systems.