The material used inside a fishing pole that helps absorb the fight of a hooked fish. Once hooked this elastic will be pulled from the pole by the fish. Elastics come in all types, solid, hollow and hybrid (a mixture of the qualities of solid and hollow) and grades. Higher number grades require more effort from a fish to pull the elastic. Bigger fish often need stronger elastic so the elastic used is mostly dictated by the size of fish you expect to catch.