Harken's Zircon Double Block with a 29 mm sheave diameter is now available in six new models, bringing the total offering to eighteen. With a maximum working load of 160 kg (350 lb) and maximum line diameter of 6 mm (1/4 in), this block is perfect for control lines requiring multi-part purchases. Designed to react quickly, the Zircon is ideal for adjustments on the go, whether it's easing the 24:1 Cunningham or moving the jib lead for more power. Trust the expertise of Harken for all your sailing needs.