These are single blocks, either of metal or internal- bound, in which part of the shell is hinged to allow a bight of rope to be inserted into the swallow from one side.
Ezi zezizodwa ibloko nokuba ilaphu okanye ibambeke ngaphakathi, apho umahluko wamakhoba uxhonyiwe ukuvumela ukutsalwa kwentambo ukuze ifakwe ekuginyweni ngaphakathi.