1.5mm thick. Includes three 23″ x 35″ mats and four mat clips. No craft job is too big for this mat, which is actually three mats in one. To assemble, simply hold two mats tightly together and affix the clips, then repeat by adding the third mat. When you're finished, unclip the mats for space-saving storage. Good for: protecting cutting surfaces and extending the life of your rotary blades.