The Frederiksen ratchet block is legendary. It is light and very strong for optimal performance. The ratchet has a small distance between each click to enhance control of sheets. This is the ideal Laser mainsheet block.
From Ronstan: The patented extruded hole design, in conjunction with the groove profile of the sheave, provides a more powerful grip than conventional designs - up to 14:1 holding power. Unrivaled low weight is achieved by the use of a Torlon® ratchet pawl, high grade machined alloy sheave and black Acetal hubs and bearings. On-Off switching knob is fitted to both sides of the swivel blocks (one can be removed if desired), and for foot blocks simply turn the sheave upside down before installation to change the sense of rotation. Unique On-Off switch mechanism can be operated under load.