Model is 3.5in x 2.5in (LxW) which seems to be the standard among USA restroom cabinet shelves. 

Holes are deep enough to keep samples from falling over but shallow enough to allow you to see the full printed name.

Works best with the shorter and wider samples but will also work with the taller and slimmer ones. I can create and upload one specific to the slimmer ones just let me know!