At last, Harken ball bearing blocks for your Laser’s mainsheet system! Boom blocks and upper traveler block feature ball bearings for rapid trims and quick eases on the sheet as you round the top mark. One-piece traveler block does away with messing with Brummel hooks and shrink wrap. To install the boom blocks, just remove both eye straps by drilling out the rivets, then replacing them with your new blocks installed. Sold as a complete kit, or individually.