The size of a Pear Shackle solely depends on the size of the chain links it is going to fit. There are ten main sizes of pear shackles, starting at 19-24 mm chain, and up to 97-102 mm of diameter of chain. They come as well in two different types, the grade 3 pear shackle, and the grade R4 pear shackle. They naturally have different proof and breaking loads.