Gen 1 Boilermaker Sight Glass O-Ring size?

[Irrenarzt]

I am in need of replacing the very top most o-ring in my 15 gallon Boilermaker sight glass. The one right underneath the big set screw at the top you remove to clean the glass. I am not interested in buying the kit as I have a McMaster order I need to place and this helps me combine the shipping costs (I'm trying to be cheap as I am opening a brewery).

Anyone know the AS568A size?

Edit: I found the list after a little digging. I should have looked a little deeper before posting. Mods feel free to delete...