These board rack mounts are machined from aerospace-grade billet aluminum and are anodized and electropolished to give you years of maintenance-free use. Designed specifically to mount the PTM Edge CBR-100 Clamping Board Racks or the PTM Edge BBR-100 Bungee Board Racks to a pipe style tower. Available in a 1-7/8”, 2", 2-5/8”, and 3" size.