Thanks for sharing that shop! I don't like the look of that knob* (I'm searching for as close to a black version of Schiit's knobs that I can find) so I'll peruse their catalogue.Depends on what Schiit gear you use it on.
Shaft is normally 6 mm. Some have screw, some are pushed on. Again depends on what gear you're referring to. 22mm is for Freya.
Search term: audio knob black XXmm
This page 16-35mm knobs: http://knobshop.com/Solid-Aluminum-Knob-SUBLIME
I referred to Schiit's "larger gear" because I thought they all have the same knob, going by the pictures on their website: Asgard, Jotunheim, Lyr, Valhalla, Mjolnir, Ragnarok, Saga, Freya.
* @Hofy @33na3rd Thanks for helping anyway! Hopefully other people who might be looking for a knob like that later will see it.
Thanks for trying.