A. The compression fit hose bibbs are designed to attach to 1/2" nominal (5/8" o.d.) copper pipe using a brass compression sleeve (ferrule) and nut. The Special Threads of the valve and nut are not the same as standard 5/8" o.d. compression fittings and cannot be interchanged. Please note: a minimum of 3/4" of pipe length is required for this compression style hose bibb to attach properly to the copper piping.