The stabilizer rails are used at the top of the pool to make the wall rigid. They also hold the liner onto the top of the pool by squeezing the coping strips on overlap liners or the v-bead of the unibead liners. Some companies use non interlocking rails which allow movement in the wall and therefore less stability. All of the pools from the Wet Spot use interlocking rails for a complete stabilizer ring all the way around the pool. These rails come in galvanized steel or aluminum.