Stand-up bases allow a wide variety of blocks to be held upright, swivel freely, or pivot so lines have a fair lead under load. The ball-and-socket design lets blocks articulate up to 45 degrees and swivel freely. The 460 and 461 bases have stainless steel reinforcement plates to handle the high load capacities of 57 mm and 75 mm Carbo blocks. Bases may be fitted with springs, but blocks won't hit the deck without them.