“Trundler” is a system of wheels to ease movement of heavy and awkward packs around a warehouse, or display units around a store, on and off a vehicle etc. The wheel concept is an injection moulded construction that can either be locked or stuck onto the base of a container with a self-adhesive pad. The unit is quick to assemble from the outside of the box / display unit and is also easy to remove for reuse or recycling once the packaging has done the job.