Simple riser/stand to put under the legs of a shelf. Interior dimension 15x185mm

I got a new shelf and it's particle board with plastic laminate for the visible surfaces, but raw board on the bottom of the legs so I needed a quick and easy way to lift it off the floor and protect the legs from water since particle board absorbs moisture and swells. I left the back open so it can sit flush against the wall and give a drain just in case water drips down inside