Rectangle Jumping Mat for 10x17 Frame with 112 V-Rings Frame Size: 10X17 Mat Size: 7 X 14 Spring Count: 112 Spring Configuration: Long Side: 37 Short Side: 19 Spring Size: 9" Step 1: Measure the diameter of your trampolines steel frame length and width Step 2: Count the number of v-rings on your trampoline mat. Long and short side, corner springs? 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).