This trampoline jumping surface is for use on a 14 ft. round trampoline with 72 v-rings and 5.5 in. springs. This jumping surface consists of UV protected polypropylene for weather resistance and is covered by a 1-year warranty. Each jumping surface has four rows of stitching and v-rings measuring 4.5 mm. Determine the size of your trampoline by measuring the diameter of the trampoline frame. Take the measurement from the outside edge of one toprail to the outside edge of the exact opposite toprail. Be sure to take two measurements in different locations to confirm your size. Please remember when measuring your springs to measure an unstretched or undamaged spring. Measure the complete spring from hook end to hook end.