1 piece valve for residential is an NPT, flanged or sanitary type ball valve. It is a form of quarter-turn valve which uses a hollow, perforated and pivoting ball to control flow through it. It is open when the ball’s hole is in line with the flow and closed when it is pivoted 90-degrees by the valve handle.
The handle lies flat in alignment with the flow when open. The 1 piece valve for residential is also perpendicular to it when closed. This makes for easy visual confirmation of the valve’s status. The shut position 1/4 turn could be in either CW or CCW direction. (S = SHUT, O = OPEN)