Features:New developed gammarus/shrimp thin skin backs, elasticsemi-transparentsegmented lines make the fly much more quintessential, a coat of UV resin makes the shrimp back durable and juicy-looking. These backs can scuttle forward on their limbs, but also propel themselves backwards with tail thrusts, so the backs can be tied in eyes to the back or the front. This is a 4 sheet (4colors) set, a sheet get 40 gammarus back shapes, each sheet has 4sizes. Size XL is for hook size: 8#, Size Large is for hook size: 10#, Size Medium is for hook size: 12#; Size small is for hook size: 14#. Packing:160pcs set (come in 4 sheets total, each sheet 40pcs)