21021 pressure and intensity of pressure demonstra

The instrument is composed of a transparent cup, sponge, pressure block, weight tray, a bearing rod, rulers, etc., instrument appearance size: φ79mm×160mm, sponge thickness is not less than 38 mm, pressure block for block 3 pcs of 60mm, 40mm, 20mm different diameter which can be replaced, weight tray diameter 40mm, bearing the pressure rod is made of metal material,Diameter 10mm, effective length is not less than 80mm, scale range 0-6cm.