Abstract: A screw driver bit includes four side walls arranged in a square cross section substantially throughout a length thereof which taper inwardly towards one another towards the apex of the bit such that the bit is arranged to mate with each of a plurality of different standard size Robertson type sockets. A corresponding socket also includes four side walls arranged in a square cross section throughout the length thereof as the side walls taper inwardly towards the apex such that the socket is arranged to mate with the corresponding bit and with each of a plurality of different standard size Robertson type screwdriver bits.

Abstract: A screw driver bit (12) and mating screw socket (18) have mating curved side walls (26, 20). The socket includes inner side walls (20) facing inward and the bit includes outer side walls (26) facing outward. The socket and the bit may both be polygonal in cross section, or alternatively, the socket may comprise a plurality of radially extending slots defining the inner side walls at respective free ends thereof while the bit comprises mating ribs defining the outer side walls at the free ends of the ribs. When the side walls of the socket are concave and the side walls of the bit are convex, a single driver bit configuration can mate with many sizes of sockets, including existing Robertson or Phillips designs. Similarly, various sizes of conventional Robertson or Phillips driver bits can be mated with a given socket size according to the present invention.

Abstract: A conventional plastic packaging member of the type including a plurality of collars for engaging around the upper flange of a drink can to hold the cans together as a group for transportation is modified in that it is formed from two or more layers of plastics material which are bonded together with a degradable adhesive. Each layer is cut through at a particular location around the collar with the cut lines of one layer being offset from the cut lines of the other layer so that each cutline is bridged by a continuos portion of the layer. On breakdown of the degradable adhesive the packaging member falls into the two separate layers which are thus cut through by the cut lines to prevent the collars or loops in the layer from engaging around livestock with the danger of entrapment.