The 75 mm Carbo has a safe working load of 1200 lbs. It releases easily under load and is perfect for mainsheet systems on sport boats like the Melges 24, J105, and Henderson 30. Carbo Airblocks are 60% stronger and 30% lighter than our classic blocks. The nylon-resin sideplates re densely packed with long glass fibers for a compact block with a high strangth-to-weight ratio. Sheaves spin on high load ball bearings with fitted races for low friction operation. Ball bearing sheaves and sideplates are UV stabilized with carbon black for maximum protection. Blocks feature Cam-Lock or U-Lock locking systems to lock the shackle in front or side positions, or swivel to keep line from twisting. Low friction carbo Airblocks are lightweight, strong, reliable, affordable. Companions to the popular Harken Black Magic line these small compact blocks have very high working loads for safe easy trimming no matter how hard the wind blows. Sideplates of high strength resin are UV stabalized to provide excellent protection against longterm exposure to saltwater and sun. Carbo blocks are perfect for the small diameter lines favored by racers