Westlake Pipe & Fittings Blue Twister® 3100005 1/2" x 1/2" Double Helix x Double Helix x MPT Irrigation Tee - The innovative Double Helix® makes the Blue Twister® swing-pipe fittings the easiest to install. No longer is there a need to hammer or walk them into the pipe. Just twist the pipe and let the Double Helix® pull the pipe onto the fitting. Once the pipe has covered all the barbs, you are assured a connection that does not leak and will withstand the water pressure of your installation.