Volume Knob for Up2Stream AMP 50Wx2

I would like to buy the volume knob add opn for the Up2Stream AMP 50Wx2 but I cannot seem to find it on the Arylic product listings? does anyone know where to find one?

https://www.arylic.com/collections/diy-audio/products/up2stream-amp-mono-board?variant=40183655366837

Here you are. Really difficult to find…