Designed to be mounted on spars or on deck, this low lead hinged block adjusts to variable halyard and control line angles to provide a proper lead. Narrow base plate allows mounting numerous blocks for multiple halyards or control leads. BB version - low-friction Delrin ball bearing sheaves allow for smooth operation under load UC version features an aluminum universal circuit sheave which combines a low friction Teflon-impregnated Nomex bearing with Delrin 107 ball bearings and is precision engineered to withstand heavy static loads, yet still run free under light loads Model #32-17 has an especially narrow profile to allow more leads to be placed side by side; its bushed aluminum sheave accepts up to 3/8" wire or rope