HPL reinvented the plastic head to make it a tougher, more positive connection between the boom and the mast. The hinge pin is 4 times its original diameter and the closure gate is 3 times burlier to stop flex or failure. In addition, the in-haul cleat teeth have more grip, but are less sharp (so as not to shred your in-haul). Two years in development, the new Pro-Level Head is a work of engineering art that’s better-built than anything else out there. You’ll find it on a new HPL boom, or you can buy it separately and retrofit to your older HPL boom (it fits most other brands of high-end carbon booms too, approximately 35 - 36 mm boom body OD at front). Detailed instructions and the new Integrated RDM shim adapter are included.