It's rubbery bark chippings!
Bonded Rubber Mulch, as the name suggests is a mix of rubber and a special polyurethane binding agent and is without doubt the most cost effective way to convert a grassed area into an extra play area. Bonded Rubber Mulch can also be installed onto tarmac, however wetpour becomes the most cost effective solution in this instance.
Made from 100% recycled rubber shards mulch has a bark appearance which makes for a natural look.
Generally installed to a depth of 50mm it gives a critical fall height of 3m therefore any equipment can be used where a child could fall from 3m