Precisely what we were looking for to absorb workout impact on our concrete basement floor. With this pack of 96 we are not experiencing any slipping or separating of the mats, but can see why a smaller number of mats would provide opportunity for these issues. No, there are not enough border pieces, but in our opinion they are purely cosmetic; so it's a bit inconvenient, but in no way affects their true functionality. This is by far the best price per square foot we could find including shipping, and the quality is high despite the fact they are thinner than the mats you can purchase at your local fitness/sporting goods store for a much more inflated price. Thanks Overstock!