The Silver series booms from windsurfing are made from 7075 high-tech aluminum. The combination of the round tube in the front and the ovalized tail section makes the entire boom 30% stiffer than other aluminum booms. Duotone is so confident that this boom is strong and stiff - they offer a 2 year warranty against bending and breakage! Boom sizes up to 160cm have a 28mm grip diameter, while the 180cm and larger sizes have a 30mm grip diameter. Even the boom grip is extra tough to help prevent scuffs when rigging.