1' 7" To 3', 15 Gauge Adjustable Jack Post, Max Ext Load 16,000 LBS, Min Ext Load 18,000 LB, Additional Support For Crawl Spaces, Attic, Staircase Or Decks, Adjusts With 3/4" Wrench, O.D. Gauge & Tube Dim 2-1/4" x 15 Gauge x 17", Screw Size 1" x 7", -5 Thread Support, Collar Size 2-1/4" x 1/2", Support Pins 1/2" x 3", 13 Gauge Plate Size 4" x 5", Corrosion Resistant Inside & Out, Double Carriage Bolt & Nut, Zinc Coated, For Added Safety, Heavy Plates Suited For Wood & Steel, Deep Dish Self-Centering Plates.