I have been using mine for 12-15 years now...It's a large green Olfa mat.
There is a tool you can get on line to keep your mat conditioned, It's by Tri-Sharp Mat smoother.
http://www.google.com/#q=tri-sharp+m...4QrQQ&bav=on.2,or.r_gc.r_pw.&fp=ccf612a4ab56e996&biw=1011&bih=597
It smoothes out the cuts that develop over time...