Theres two different types. Theres dendex which is green bristles attatched to a metal frame made in diamond shapes. This holds an edge well but it hurts
like fuck when you fall on it. The other type is called snowflex which is white mats with short softer bristles on it. Its also usually put on a cushioned surface so it doesnt hurt that much when you fall on it. The problem is you cant hold an edge on it very well so you have to go straight. This stuff is used to make kickers and good stuff out of and its not too bad.
Snowflex hit in Edinborough