Harken 40mm Carbo Ratchet Block holds lines securely with an eight-facet sheave.Carbo Ratchets allow sailors to hand-hold loaded lines and offer balance between holding power and controlled easing. Lightweight Carbo Ratchets are available in 40mm, 57mm and 75mm sizes. All the Carbo Ratchets feature a recessed On-Off switch that is easily operated from either side. The 40mm cam-arm versions work in ratchet mode only. Commonly 40mm blocks are for jibsheets and spinnakers on small dinghies.The 40mm, 57mm and 75mm Carbo Ratchamatic is adjustable for many applications and weather conditions. The load-sensing ratchet block rolls freely in both directions under low loads, then engages the ratchet automatically as loads increase. With 180 degree wrap, you get a 10:1 holding power.Key FeaturesRatchet blocks are hand and crew saversAllows a line to be eased instantly with controlOn/Off switch allows the ratchet to be turned off in light airHardkote-anodized aluminum sheavesStainless steel swivel shackleSheave Diameter: 1 9/16" (40 mm)Max. Line Diameter: 1/4" (6 mm)Max. Working Load (MWL): 300 lb. (136 kg) Breaking Load: 600 lb. (272 kg)Weight: 4.7 oz. (132 g)Length: 4" (102 mm)