A is the one i was talking about which comes together with the FPR, it's threaded/removable just not sold separately and has an o-ring see the video from min 12.40, you should find one on a scrapped FPR which was replaced due to valve leak... then to see it's to the cooler from 21.30 : https://www.youtube.com/watch?v=5o0OKvf5QQM

