1", Jar Top Anti-Siphon Valve, Jar Top Bonnet For Easy Cleaning & Maintenance, External Bleed To Flush Dirt & Debris, Threaded Bonnet Provides Easy Removal With No Screws, Drop In Diaphragm For Effortless Maintenance, Reverse Flow Feature Ensures Valve Shuts Off If The Diaphragm Tears Or Rips, Reduces Risk Of Landscape Flooding.