The Plumber's Choice 4 in. Anti-Siphon Sillcock Frost Free Outdoor Faucet with 1/2 in. MIP/Sweat Connection and 3/4 in. Hose Bib SILLVAC4 - The Home Depot
How to Fix Anti Siphon Valve on Faucet - YouTube
What Is An Anti-Siphon Valve and How Does it Work?
Sillcock hose bib and vacuum breaker - DoItYourself.com Community Forums
Hose Bib Backflow Preventer Vacuum Breaker,Garden Hose Check Valve to Connect 3/4 Inch Outdoor Faucet Spigot,Sprinkler,RV,Anti-Siphon,2 Packs
2pack Vacuum Breaker Set 3/4 Inch Antisiphon Hose Bib Valve For Garden Spigot
Hose Bib Backflow Preventers and Vacuum Breakers - Nonprofit Home Inspections
Woodford Model 17 4-in L x 1/2-in Copper Sweat Brass Anti-siphon Frost Resistant Push/Pull Sillcock in the Sillcocks & Hose Bibbs department at Lowes.com
Hosebib Adapter ADP2 1-1/8" fine thread for Arrowhead Brand Hosebib | eBay
Arrowhead Brass 485LF – Arrowhead Brass and Plumbing, LLC