rubber bladder for expansion tank,SGS,ROHS and PAHS certified 1) made from natural rubber, butyl rubber or EPDM2) 2L, 8L, 19L, 24L, 50L, 100L available 3) long life time (100 thousand times)4) SGS,ROHS and PAHS certified5) already well sold in US,Italy and Russia rubber bladder for pressure tank