Two designs to choose from . The right ring is slightly lighter though appears larger and has a split shank detail on either. The left ring has a slightly smaller head, but has a heavier solid shank .

Right Skull average weight: 4.3 grams    Skull length: 1.6cm   Ring sizes: L, N, P, S

Left skull average weight :   7.8 grams     Skull length: 1.3cm  Ring size:  L, T