Guys imeo mentioned this before but I will mention it again. Clear window of ithaka doesn't need Orings. He put Orings for the people who are afraid to crack the window because of a lot of unscrewing and screwing. once you connect the two metal parts to the clear window with Orings, it becomes difficult to remove them. Therefore screw the metal parts to the point where the oring doesn't show, and then you never have to unscrew the metals from the plastic ever again and it will be very difficult to separate them, they become 1 piece. If on the other hand you don't want them as one piece, remove the Orings, it will not leak. The last version of UFS didn't have Orings and never leaked.