A chasing-arrows triangle around the numeral 5, identifying polypropylene.
The numeral 5 identifies polypropylene — tubs, bottle caps, food containers. Acceptance is improving but still varies sharply between collection areas.
Three arrows chasing one another around a triangular path, enclosing the numeral five at the centre.
Both are built from triangles, arrows and number like forms, and both are used in packaging contexts.