I bought this for two flooring projects, 1) above the subfloor and 2) a room with under the floor. The \"above the subfloor\" went onto new OSB sturd-floor in a portion of a cabin that is 100 years old. I didn't trust the floor joists to hold k-crete. So I put 2\" styrofoam with foil face under the floor and sealed it with spray foam from can. I laid down the transfer plates between 3/4\" plywood sleepers and put the pex inside it. It went down smooth and with the pex it sits a hair below the plywood. The old cabin floor still moved alot and the 3/4\" plywood sleepers being screwed and glued really stiffened it up! Glad I did it this way. No need to worry about tight tolerances between the plywood sleepers, it's better to have a little leeway, 1\" gap is fine. I initially tried getting close to really sandwich the pex and transfer plate in but it was more work then gain. I am not sure what the blue plastic coating is on the transfer plate, we peeled it off in most cases, but left some on. We we were laying the transfer plate down into the gap so the blue was on the down side. The u-turns, I call them, are where the pex turns around. This gap is 5/8 wide and deep. The pex fits tight in that. Holds it in place. Those were router with bushing guide and a template I made. I put underlayment over the transfer plate/pex to smoothen it some. Will put floating LVP over that. Be very careful to not hit the pex when stapling. Mark out the underlayment where the pex is. Made sure I put a few staples in the transfer late too, just to hold it. I originally ordered 100 plates from eBay and it was supposed to be Omega, it wasn't. But the eBay order said faster shipping, like a week. I used them with no issues, they were Vevor. So for the same price I ordered the next batch of 100 from Amazon. Amazon indicated 2 weeks shipping time, they arrived in like 6 days. I don't see where the Omega will help that much. I'm sure there is some physics involved but these fit t