HELIX 2-Sided 12" x 8-3/4" Self Healing Cutting Mat Why are cutting mats better than physicians? Because they really can heal themselves. This 12" x 8-3/4" self-healing green vinyl mat from Helix has one 4x3 2" grid and one 4x2 2" grid, both with 1/4" hash marks on all four edges, plus 5 1/4" lines between the grids. Double-sided cutting surface, the second side is blank.