Got this via email today: New and Improved PGV-ASV for the California Market Hunter Industries is proud to announce the new and improved PGV-ASV for its California market. Totally redesigned to be the toughest valve in its class, heres all thats new: * Durable glass reinforced nylon bonnet * Six-bonnet bolt design * New cap design incorporates more supporting ribs for a significantly stronger performance * New material provides higher strength and performance in high heat site conditions I don't know why they decided to redesign it except to look more like the Rain Bird ASVF. I took aprt and cleaned debris from 2 Hunter 1" inline SRVs a couple of weeks ago that I installed 10 years ago... still going strong. Diaphragms (white) were intact and pliable. The four bolt PGV seemed to be an update of that valve, and the ASV was essentially that valve with and A/S added. Only problem I ever had was with the inlet/ outlet threads of later models.