High Flow Rate Inline air gap with 1/4-inch FIP or 1/2-inch Thread Inlet and 5/8-inch Compression Fitting or 3/-inch Thread Outlet. (AG150-002, 211212, GAP-A-FLO)

This little air gap was recommended by a company that makes reverse osmosis systems so I picked one up to try out. It works as it should but you do need to keep the vent window rotated around just right or water will splash out.I will get one again if I need it.

I honestly had the same thing happen as another reviewer on the regular version, water just flowed out of the gap. I was pissed. Then I got to thinking about my adapters. Sure, it was 3/4 fip out, but to a 1/2 barb. I realized the backflow made sense as the water was going from smaller id to larger id back to smaller id. I grabbed a 3/4 fip to 3/4 female pvc adapter, used a short run of 3/4 pvc from air gap to drain, and voila. Not a single drop of water out of the gap. Parts were like $6 total from hardware store, for both the drain lines pictured. So with either version, use larger diameter out than in.

Excellent construction, fit, and finish!