I have bought a couple of the Garhauer #40 light ball bearing long shackle blocks for my boat and love them. I will probable replace all the turning blocks with the Garhauer SL blocks eventually. The #30 are probably adequate but the #40 are very rugged. They have a 5/8" schackle with a 1/4" pin for mounting. I also replaced my dual deck organizer with a quad (fits the same holes as the dual. I had UK replace the slugs on the main and can easily raise the main from the cockpit without using a winch. There's virtually no friction in the system. For a 34, I think batcars just add weight and cost.Call Guido at Garhauer. He's always been happy to take my money. Ph 909-985-9993