These fittings provide excellent corrosion protection. The fittings have a special O-ring made from HNBR and are resistant to gas. The fitting housing consists of CW617N brass. The fitting has a separation ring to prevent direct galvanic contact between the aluminium of the pipe and the brass of the fitting. This prevents electrolysis. The fitting has O-rings made from EPDM and stainless steel press sleeves with 3 inspection holes. To prevent assembly errors, the stainless steel press sleeves come with the size and type of press profile that allows pressing.