The stilts is defined mainly by a flat spring controlled upon deformation, so that the result is a straight movement relative to the ground. With the riser's functional principle, depressive spring characteristic and backward movement of the force point during deformation are achieved. This supports the natural force point movement in the heels direction at higher loads and allows the runner to transpose his optimal jumping energy. Hence, you can really fly. Specification Measurement: 91cmX29cmX40cm N/W: 7KG/pair G/W: 8.5KG/pair. Flyjumper is made strictly according to human's weight.for the learners, the suitable model will be the same weight to the user's weight. If the user need to do some flip or jump high up in the air,you have to choose one that 10-20kgs heavier than your body weight,otherwise,the spring of flyjumper will be easily damaged. Please choose the suitable model according to your real situation. Certificate: ISO9001: 2000 /CE Packing: one pair/carton Lead time: 1.usually within 1 working days for samples after the receipt of prepaying money. 2.usually within 15 working days for bulk order after the receipt of deposit. But the exact time of delivery must depand on the actual produce condition of idiographic product at that time Load Quantity/Container: 410Pairs / 20Ft Container 870Pairs / 40Ft Container 950Pairs / 40Hq Container Mini Order Quantity: 30 Pairs Warranty: 6 Months.