Harken Midrange Stand-up Toggles The 1561 holds blocks upright. The 1638 holds blocks upright and allows attachment of control blocks. Toggles include 1/4" (6 mm) and 5/16" (8 mm) mainsheet block pins. They accept 57 mm and 75 mm Carbo doubles and triples, 75 mm Carbo singles, 3.00" Small Boat single, Fiddle, Midrange blocks and 57 mm AirBlocks®. To attch Carbo control blocks to the stand-up toggle, choose 1626, 1627 cars or 1638 toggles