While not actually a stainless steel coil, cold plates are thin profile aluminum blocks in which stainless steel tubing is embedded. There is total surface contact between the 22' (11' per line) of embedded stainless tube and the cooling aluminum which makes plates the most efficient method of cooling per foot. However you get far more volume in a stainless coil that is 3/8" x 50" long so coils will out perform plates. Why do we sell plates? They are great in low volume applications where space is an issue. If your draft box is for a couple buddies during camping, plates will work fine. If you want to serve beer at a company picnic or a party you are better off with the coils. We use plates in our famous rolling TIKI HUT bar because we need a low profile method of cooling beer inline to the faucet. Check out the About Us section to check out the tiki hut!Inlet and outlet fittings are 5/16" x 1/4" flare. 1/4" flare connections on the outside, 5/16 threaded into the plate.