This mat is the perfect size for my needs allowing sufficient space around the chair to move around. The lip fits well under the desk. The surface provides for smoother moving but is not slippery. It is barely noticeable on the hardwood.
The mat is not as thick as I need. It is better designed for a very low pile carpet. My chair sinks in and leaves dimples in the mat. Take my advice and get the next grade up.
From the catalog appearance it would seem that the extension that goes under the desk is not long enough to protect the carpet. If you did not position it just right I would think your chair wheel would come off the front edge also if you are a person that likes to sit up close to your desk. A shorter person might not find this useable. The other big gripe with these mats is when they crack. The plastic needs to be thick enough to protect the carpet but not become brittle. It is also a problem when bits chip off the edge of the mat because it gets brittle and your chair wheel cracks them off.
I purchased this carpet chair mat for my home business office. It is THE WORST chair mat ever!! The "teeth" on the bottom DO NOT keep the mat in place and the mat ends up sliding all around. It either ends up bunched up against my desk or my chair gets caught on it because it keeps moving around. The one end that keeps bunching up against the desk is almost permanently bent because of how many times it has bunched up against the desk and the mat is only a week and a half old! Whatever you do DON'T purchase this chair mat; it is AWFUL!!