The mats I received have a “this side down” sticker applied to one side. What is the difference between the side that meets the floor and the side that faces the ceiling?

We give directions on which side is the top and bottom so that the color texture and shade are consistent when a customer purchases more than 1 mat. The production process adds a sheen to one side. When a customer purchases multiple units we want to make sure that the customer has both mats facing the same way to give a consistent shade.