Anti Siphon valve has a backflow prevention device inside, this valve acts as a backflow and a valve. If you decide to use inline youwill have to install another backflow preventor, before the valves. Remember for these to work properly, you must install them 6" above the highest sprinkler head!!
Thanks
Ray
Rays Above and Beyond Automatic Lawn Sprinklers
Thanks
Ray
Rays Above and Beyond Automatic Lawn Sprinklers