Corny keg seal replacement

[bicyclerepairman]

So I'm finally getting around to replacing the seals on my corny keg. The seal kit has 3 types - the lid, the outer post seal, and a slightly smaller one. I can't work out what this smaller one is for - the only other place it might fit is the dip tube, however the existing seal on the dip tube is square section, but the new one is round. Any ideas?

Thanks in advance!

[Cazamodo]

They are for the dip tubes.
I ordered a bunch of the red seals, and got them for lid, posts, and dip tubes. Some of my dip tubes had the squarer o-rings, some didn't. I still replaced them all and never had any problems!

[bicyclerepairman]

Thanks! I went for it, and everything seems ok. Did a quick leak test and couldn't see any bubbling.