A chasing-arrows triangle around the numeral 3, identifying PVC.
The numeral 3 identifies polyvinyl chloride. It is rarely collected domestically, and its presence in a mixed stream causes problems for the recycling of other plastics.
Three arrows chasing one another around a triangular path, enclosing the numeral three at the centre.
Both are built from triangles, arrows and number like forms, and both are used in packaging contexts.