Plumbing - PEX ShutOff Half Inch
These will be mounted in the bathroom/kitchen/utility cabinets under the sink.
They are available with screw mounting lugs but they cost twice as much...
1/2" PEX Crimp Drop Ear Ball Valve (Lead Free)
http://www.supplyhouse.com/Raven-806P012-NL-1-2-PEX-Crimp-Drop-Ear-Ball-Valve-w-o-Drain-Lead-Free $7.61
1/2" PEX x 1/2" PEX Ball Valve, T-Handle (Lead Free)
http://www.supplyhouse.com/Everflow-615P012-NL-1-2-PEX-x-1-2-PEX-Ball-Valve-T-Handle-Lead-Free $3.88