Harris 3/16 x 12 ft Grade R Twin Welding Hose with 9/16", standard "B" size fittings. This is quality rubber hose capable of 300 PSI. It is for oxygen and acetylene only. The 12 ft long length is designed for use with port a torch outfits. However, some port a torch (mainly older models) have "A" sized fittings which are 3/8-24 thread.
