Harken 57mm Carbo Air® Fiddle Ratchet Block is a good choice for 3:1 and 4:1 tackles on dinghy vangs and mainsheets.
Carbo Ratchets blocks 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 57mm blocks are for jibsheets and spinnakers on medium 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.
