do they do a 20mm invisible one way shower tray ?
Dear Andrew,
OneWay sloped shower trays are only available in 30 or 40 mm thicknesses, because of their technical specification.
If you prefer 20 mm thick tray, please see similar sized 4-way sloped tray here:
Showerlay Wiper 900 x 1200 mm Line Invisible
It's default thickness is set to 20, it can also be 28 and 35 mm thick.
I am happy to assist if you have any questions.
Kind regards