There's two compounds called Guey Gluey (which is the softer compound) and ORC (which is the harder compound) i think.I've ran the Guey Gluey compound twice now, love it .My last one lasted me about 4-6 months, and this current Big Betty is begining to show signs of wear after about a month.They have awesome grip, and a much better feel to any tire i've used :turned:I have only ever pinched my tube once with these tires .At 2.4" it has a reasonable size, not too wide, not too narrow.It's the only tire i think i'm ever gonna use on the back, although i am also using my old one on the front for a bit....Also they are light at around 800-900g I haven't heard of many other people use them, but in my opinion they are an awesome tire