The tiny wheels are plastic and just click in so, no rough stuff.
It doesn't come with instructions and you don't need them to put it together, it's very intuitive and easy.
I'm very pleased, and hope to find a slightly less wide one for my spices to go on the other side of the fridge.
I'm glad I can wheel this between two higher objects, because something tells me that my cats would knock it over constantly if it weren't being slotted into a space.
That's a real considering for people with kids and pets looking at this...I wouldn't free stand it.