11' 11" (143") Round Trampoline Mat With 100 Rings Takes 8.5" springs Springs NOT Included Frame size: 14ft We use grade A polypropylene constructed of high quality materials to ensure your kids will be bouncing safely for a long time. (mats do not include springs) How to Measure a Trampoline Step 1: Measure the diameter of your trampoline's steel frame. Step 2: Count the number of v-rings on your trampoline mat. Step 3: Measure the length of your springs (note: to measure correctly, remove the spring from your trampoline and measure the length from hook-end to hook-end).