aesPRES GAShttps://www.racmet.com/en-ww/aes-pres-gas.aspxThe aesPRES GAS fittings range is also internationally certified by the most accredited international bodies, with specific tests for natural gases. ... The yellow O-Ring can be easily used at -20°/+70°, maximum pressure 5bar PN5/GT1 with the same quality and safety.