Connect brass or poly PEX crimp fittings to PEX piping securely with these pure, annealed black copper crimp rings. They are specifically made for use with 3/4 PEX SDR9 tube and comply with various industry standards, ensuring reliable performance. The crimp connection method allows for a strong and leak-free seal, making installation straightforward. These rings are an essential component for any plumbing or heating system using PEX.