Abstract: A jet assembly has internals rotatably and releaseably fit to a jet body, such as that for a spa. The internals have a barrel housing, a rotor and a barrel inlet. The internals as screwed into the jet body. A first threaded portion outside the barrel threadably engages second threaded portion inside the jet body wherein the internals have delimited rotation therein to align and misalign the barrel inlet from a body inlet on the jet body to control flow on and off respectively. The threaded portion within the jet body can be a locking ring affixed therein by fasteners or integral with the jet body. Rotation can be delimited by a projection on the barrel and a cooperating annular delimiting surface on the locking ring, such as circumferentially-spaced detents.