This kit of two castor units is an installation aid to assist in moving, installing and manoeuvring large and bulky HDODF's in Exchanges. They bolt either to the bottom or side of a HDODF, and are installed before the HDODF is moved off its pallet. The units enable two craftspeople to move a HDODF along in an Exchange or CO, either by the bottom or side. Each castor has three, individual locking positions. First: wheel locked, can not rotate. Second: castor wheel freely moves and turns. Thirdly: castor locked in a 90o position, but wheel can rotate. By using proven OH&S ergonomic handling techniques, a HDODF can be moved from its pallet to its position in the Exchange (or CO). By tilting the HDODF, and placing a piece of packing wood under it the castor installation aids can be quickly removed from the HDODF, thereby enabling the HDODF to be manoeuvred into its final position. Whilst moving a HDODF select the route carefully, and watch out for both overhead and floor obstructions.