2-Pack Brass Vacuum Breaker Set 3/4" Anti-Siphon Hose Bib Valve for Garden Spigot RV Hose Connection Backflow Preventer Connector with Tape and Extra washers

Works as described.

Good value with these kits. Originally, I installed them too tightly on the spigot and they would not release any water when I turned the hose bib off on a hose with a pressure nozzle on the end (pressure was still in the hose with the nozzle closed). I posted a question about this and it was suggested that I might have them on too tight. I backed off a bit, and now they work. If this happens to you, just loosen the vacuum breaker bit by bit when there is pressure in the hose... you'll find the sweet spot.They work great now!

The product is sturdy. The install process is simple, but the "screw in place" theory isn't very productive, screw doesn't increase effectiveness.

Does the job.

Nicely Made. No matter who makes these units though they do not survive my winters. If I don't take them off every fall, the next spring when you turn on the water they sound like a lamb being eaten alive by a coyote. To my surprise the locking screws are English standard 10-32 fine thread. So you can replace them with Allen head set screws or either Allen or Hex head cap screws. I would suggest that you use stainless steel fasteners, particularly if you live where road deicing salt is used. I attached two images showing the original hex head screws, one plainly visible and the other screwed into a 10-32 National Fine thread USA threading die, and one image of the end desired result with the two units shown end to end for posing ease. If you are unfamiliar with thread specifications just download pictures to your phone and show them to a hardware store employee and they should easily understand what you want to do. The new screws may seem a little pricey however the cost is trivial compared to removing and soldering on a new faucet.

After I shut off the hose they don’t drain the water from the line, If anyone has a suggestion, let me know

This is the most common design of the backflow preventer for a hose bib - a simple valve that lets water out of the bib but not back in. They are all built with the same design and parts so get the cheapest available. I like this one because it was not only cheap but also included hex removable set screws. This should keep the code cucks happy.

The brass quality, and finish, functionality seems all good.I don't personally like these devices and removed them years ago (until our city is now requiring them) because they allow water to vent/spray when you are sometimes standing near the faucet after you turn off the water valve to the garden hose. Even though the spray is directed toward the house and away from you you will feel the splash from some of the spray, though, these are slightly (slightly) better than the past bib valves that came with our home when new.Another reason I bought these over others was because of their quality silicone O-Seals (vs. the traditional rubber O-Seals which get hard/leak after a couple of years) that came with this item.To install it, you make sure to push one of the O-Seals into it and simply screw it on to your outside faucet - and, then tighten the set screw with pliers so that it won't come loose when you add/remove your garden hose to/from it in the Spring/Fall.