Bottom plate is 10" x 10". Holes are 8.25" center to center. Top plate is 7.5" x 4". Spring is 13 5/8" long and spring with boot is 15" long. The diameter of the spring coil is .5" and the diameter of the spring is 5 5/8". This product should last 2 years in harsh conditions and up to 5 years in optimal conditions. Some conditions may require replacement sooner. Tensile strength is 1200 lbs.