There is one mat in the set. This mat holds up very well. My son is 3 and kicks it all the time. It is showing some wear now but still looks pretty good. It matches well if you interior is grey or black.
Just one, but the price is right. Like Rachel said, they hold up really well and it is black so it blends in if your interior is dark. Thanks for reminding me - i'll need to order a second one for our upcoming addition to the family!
If you want 2, you need to buy 2. There is no set. That said, this is the only back seat protector to buy. The others we bought fell apart in weeks. These are still going strong months later. Everything about them is made to withstand just about everything kids can dish out, including pulling on them to get into our SUV.