Excellent hard floor chair mat. We purchased two (in different sizes) for our small office. The mats lay flat do not slide and are made of great material. I would recommend this purchase of Staples brand mats.
Only reason I didn't give it a higher number was that I think the "nubs" on the underside designed to keep the mat in place on the carpet they could be a bit smaller - when rolling across the mat on the desk chair you can feel the "nubs" and over time this is where the mat fails cracks and needs to be replaced.