A half shell block with a single sheave bolted to a mast or other object which serves as the other half shell or cheek. Usually used in connection with halyards.
Ibloko esisiqingatha yeshell enevili elinye elihamba ngentambo eqiniselwe kwimasti okanye eny into esebenza njengenye ishell esisiqingatha. Idla ngokusetyenziswa ngokudibene nentambo yokuhlisa nokunyusa iseyile.