Preferred valves can be skirt valves, which possess numerous advantages over {TAIL ~ known one way valves} such as umbrella valves and {HEAD ~ duckbill valves} 
Preferred valves can be skirt valves , which possess numerous advantages over { TAIL ~ known one way valves } such as umbrella valves and { HEAD ~ duckbill valves }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD