Expansion shell

Claim 1

An expansion assembly which is adapted during use to be expanded into contact with the wall of a hole in which it is placed, comprising: a first shell member of generally tubular shape, the member having a first end which is inclined to its longitudinal axis from a first position at which the wall of the member has substantially its greatest axial length to a second position, diametrically opposing the first position, at which the wall of the member has substantially its shortest axial length, the first end being disposed substantially in a plane, the member being formed with at least a first line of weakness in its wall which extends in the axial direction of the member and with a formation positioned at the first end where the wall of the member has substantially its greatest axial length, the formation projecting out of the plane of the first end; a second shell member that is substantially identical to the first shell member; and an elongate member passing through the first and second shell members, the shell members being arranged so that their first ends respectively are opposed to and in contact with each other and so that the formation of each shell member engages the first line of weakness of the other shell member.