What to land on for stunts/acrobatics?

My brother and I attend an open gym every weekend which is at a gymnastics center so you can practice acrobatics and hopefully not get hurt. There are mats there that are pretty large, probably about 5ft x 12ft x 6in. We use them when dismounting from trampolines, rings, and attempting stunts. What kind of mat is this and where can I buy one like this for home practice? How much would one cost around the described size?