PEX clips provide excellent holding power. The 3/8" and 1/2" can attach together laterally for tight installations. PEX clips attach under the wood subfloor for joist-heating applications. The clips prevent the tubing from coming in direct contact with the subfloor, eliminating the possibility of creating uncomfortable hot spots on the floor above. Drywall screws are commonly used to secure the clips to the wood subfloor.Note: Select a screw length that does not penetrate entirely through the wood subfloor once installed.