This is one of my 4 into 1 water manifolds. It's set up for 4 #10 o-ring fittings (but you can use a combination fitting that is up to #12) and 1 #20 o-ring on the opposing side.
I also make a 2 into 1 water manifold. It uses 2 #16 to 1 #20.
Both have provisions for NPT for water temp pick up.
