I have been to two plumbing supply shops in town and they have no idea who makes this. I hope the ng can help.
Based on my own research it might be a Mansfield product.
The following six links should show the pictures
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Full is the whole thing
Front is the part of the valve which protrudes from the wall
Deep is the piece which is deep inside the wall
Handle is just that
Side is a side shot of the handle
Top is the top of the Anti-Siphon / vacuum breaker
A google search of the info on the top of the Anti-Siphon valve is what lead me to the possibility of Mansfield.
Thanks for looking...