The Harken 40mm Carbo Air Fiddle Block with Swivel (Part No. 2655) has a sheave diameter of 40 mm (1 9/16 in) and can accommodate maximum line diameters of 10 mm (3/8 in). With a maximum working load of 220 kg (485 lbs), these lightweight and reliable blocks are an affordable option for a variety of sailing needs. They are often paired with the popular Harken Black Magic line and can handle high working loads for safe trimming. The 40 mm fiddle configuration is ideal for 3:1 and 4:1 tackles on dinghy vangs and mainsheets, as well as for controls like cunninghams and internal boom outhauls on larger vessels.