So I joined AphaCool's forum to ask for the correct o-ring size for their standard G1/4 threaded fitting and instantly get banned for spamming/bot, maybe for posting links to their own products on their own web page. Is this where we are in the industry? Anyway maybe NBR 11 x 2mm as shown here but oddly states "without groove" https://shop.alphacool.com/en/shop/fittings/accessories/roh-o-ring-11-x-2mm-g1/4-inch-without-groove Anyone have a solid McMaster o-ring replacement they've used, I buy in bulk for maintenance replacement. The o-ring is pictured below fitting is 17226 as an example but likely their common size.