1.hollow jack base Product detail:Screw Jack base which adjust the support height is part of scaffolding. Screw jack which is called as U-head jack base, Screw jack base, Adjustable jack base play the role of the support. Product size:Screw SizePlate SizeFeatureØ38*4*760mm50*150*5/6mmMaterial: 40#,Q235. Surface: Hot Dipped Galvanized, Electro-galvanized,Painted. Standard: EN1004:2004,AS1577,BS EN12811-1:2003Ø38*4*660mmØ38*4*600mmØ38*4*400mmØ48*4/5*820mm150*150*8mmØ48*4/5*600mm2. hollow u-head jack baseScrew SizeU-head SizeFeatureØ38*4*780mm150*170*80*5/6mmMaterial :ASTM A53,Q235 Surface: Hot Dipped Galvanized, Electro-galvanized. Standard: EN1004:2004, AS 1577,BS EN12811-1:2003Ø38*4*760mmØ38*4*660mmØ38*4*600mmØ38*4*400mm150*120*50*5/6mmØ48*4/5*820mm150*120*50*8mm Ø48*4/5*600mm