Low-profile mastbase halyard lead blocks can be grouped in a small area at the mastbase. Fixed blocks lead halyards and control lines aft, allowing crew to raise or lower sails, or make tuning adjustments from the cockpit. Pivoting versions feature a hinged construction, providing crew a fair lead to a choice of winches for halyard and line controls.

Over-the-top blocks lead lines aft over cabin houses, coamings, and splashguards.