We purchased the first one from Staples. We were in need of a second one and actually bought a Rubbermaid. Took the Rubbermaid back to the store and went back to Staples to get one just like we got before. This is firm enough (Rubbermaid was flimsy and to soft - chair wouldn't slide smoothly) works well chair moves smoothly and the mat has a comfortable feel on bare feet. Would recommend to others.
My carpeted floor is a little too soft for this mat. I like all the features but find indentations at contact points of chair. I suggest you make selection/ mat thickness based on flooring.