This is a set of snap-on paper towel holders (left and right) for Trinity NSF wire shelving. This design supports shelves with 6mm wire edges and outer-outer spacing of ~29.5mm. Will snap onto the outer shelf edges as pictured. Place the top (long) hook over the upper wire and then rotate down to snap onto the lower wire. They fit snugly but add a wall if you'd like them to fit more snugly. I've had no issues with 2 walls in PLA, which is the uploaded designer profile. If you want drag on the roll, push them up against it, and spread them a few mm further apart for the roll to spin freely.