... ,making tension test Tension force:custom. Item nameTennis ball with elastic string and computer stringMaterialPolyster/LatexDiameter0.45mm-0.5mm ColorBlack (we can ... you Core Material Rubber; Latex; Spandex, as per the client's request Rubber/Latex 23#,28#,32#,37#,42#,52#,63 ... .0mm Package 100m/tube,200m/tube,300m/tube as customer's request Package tool paper straight tube, paper pagoda tube,rubber ...