I bought a big type. Although it is caster attachment, the fitting part was terribly hard and could not be assembled. If you put it forcefully, either one will be distorted, so I think that I will stick to it if I work harder. The caster body is a type with its screw hole open on all sides, so you can use it for something. Although there are various tool boxes, I can recommend it for those who feel that the pull-out formula is slimy.