Fitting ( solds as set of two each ) is made to connect to the Valve or By Pass Valve for Clack WS1 Valve and other "brands" that use the Clack type of valve under their private label.
Brass Fitting can be "sweated" to 1" Pipe fitting. If using 3/4" copper, then a 1" x 3/4" reducer is also required ( and can be purchased locally at plumbing supply company ).