The 2-1/2" dielectric nipple is designed for use in water heater inlet and outlet hook-ups, and for other uses where dissimilar metals occur in piping and plumbing systems. The thermoplastic lining helps prevent corrosion and the ends are 3/4" NPT tapered pipe thread for a fluid-tight seal. Dielectric nipple measures 2-1/2" in length and is sold in a convenient 2-pack.