Adjustable, easy-to-assemble, easy-to-install floor jacks are designed for use during remodeling projects to reinforce stairs, porches, decks, or weak floors. Constructed of premium quality steel and coated to prevent corrosion. All moving parts fit snugly to avoid lateral displacement and the top and bottom plates are deeply embossed to mitigate movement and prevent dishing. The heavy-duty high-carbon steel is double locked for added safety. Compression strength is defined as testing to the point of failure. To determine safe or allowable load consult a licensed engineer. No. C-2: Adjustment Range: 210" to 47", Compression Strength: 14,000 lbs at maximum extension, Material: Steel No. C-3: Adjustment Range: 17" to 30", Compression Strength: 16,000 lbs at maximum extension, Material: Steel No. C-4: Adjustment Range: 10" to 14", Compression Strength: 18,000 lbs at maximum extension, Material: Steel No. C-79: Adjustment Range: 46" to 79", Compression Strength: 11,350 lbs at maximum extension, Material: Steel No. C-84: Adjustment Range: 48" to 84", Compression Strength: 9,100 lbs at maximum extension, Material: Steel No. BIG MOE: Adjustment Range: 48" to 84", Compression Strength: 38,000 lb minimum ext, 20,000 lb maximum, Material: Steel