This kit contains three Jack Plates weight capacity of 20-100 Tons (Three plates with three different tonnages) No more cracked, warped, bulky wooden blocks!! Lightweight - only 5 lbs. Corrosion & rot-proof. Will not absorb moisture. 55 ton weight capacity. Will support a 55 ton Air Hydraulic Jack. Will not break under load, mushroom, or warp. It works with all types of jacks and doubles the surface area for jack to sit on. Great in soft earth or uneven ground. Lifetime guarantee against breakage. Allows Employer to comply with OSHA Regulation 29 CFR 1926.305 "Blocking for a Firm Foundation".