Head shower rubber parts: Material: silicone rubber.Without any harmful substance.Can not cross water column Rubber MaterialNBR,EPDM,NR,SBR,Silicone,Viton/FKM,ACM,FPM,FLS,PU,HNBR,etcHardness30~90 Shore AcolourAny colourO-ring sizeAS568, JISB2401,Metric,GB,etcGasket sizeCustomizedBrandXSLaboratory EquipmentTensile Tester,Rheometer,Measuring Projector,Heat Aging Test Machine,Constant Temperature ...