This block could be open from both side. The size is from 3″, 4″, 5″, 6″, 8″, 10″, to 12″, the working load from 1T,2T,3T,4T to 5T, and the Diam of Rope from 16MM to 36MM.
It is suit for small working load limit lifting work.
Pulley and Block are common lifting mechanisms used for rigging and can use with Wire rope or Nylon rope or Chain.