Addis506985 Premium Tidy Drawer Soft Base Storage Boxes, White Grey, Set of 3, 18 x 40 x 7.5 cm

The smallest tray is not a square so how can it be 17 x 17 x 5.5?

what are the exact external dimensions of eavh of the three trays?

Does anyone know if the non slip surface at the bottom is removable like a insert/mat or is it actually built in as part on the tray?

Is the soft interior water-proof? Could you keep a damp cloth in it under the sink?