RDG stands for Reduced Diameter Grip. Chinook reduced the grip diameter another 2mm from our standard small diameter Pro-1 Alloy Booms. This model has a consistent diameter throughout the arms. The addition of absolute length markings on a 60cm tail-piece aid with rigging your sail properly. Exceptional torsional rigidity and fits both standard and reduced diameter masts perfectly. One year warranty. 150-210cm Monocoque body Fully articulating head Absolute length markings Positive snap-in skinny adapter Modern bend curve Rounded front curve makes hand transitions during jibes, tacks, and the most advanced freestyle moves feel natural Grip Diameter: 27mm - 1 1/16" Weight: 6.3 lbs Inside Width: 41cm