When ordering multiple mats you can permanently fuse them together with Seam Weld. Makes a water tight seal between two mats. Simply install the mats with a slight gap between them, about an 1/8" and when the mats have fully settled and are in their final resting place apply a bead of Seam Weld and let dry. Seam should be dry withing 2-4 hrs. Covers up to 100' at 1/8".