a control ring having a wall with an inside and outside surface, said {HEAD ~ control ring} rotatably fitted into said housing cavity, said control ring having a vent in {TAIL ~ said wall}, said vent communicating with said outlet port 
a control ring having a wall with an inside and outside surface , said { HEAD ~ control ring } rotatably fitted into said housing cavity , said control ring having a vent in { TAIL ~ said wall } , said vent communicating with said outlet port
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH