B&K Compression Galvanized Coupling for general utility on small piping such as that used on machinery equipment, well work, pumps, compressors, engines, etc. These couplings require no threading, no exact pipe fittings and each coupling will absorb expansion or contraction without leakage. Hydroformed steel body, rubber compression gasket, and metal friction ring, rated up to 125 PSI at 210 degrees F., iron pipe size for piping or repairs on galvanized pipe.