a counter - balance weight for a modular safety rail includes a solid body of a compact shape which defines a substantially planar major surface which , in use , is intended to rest on a support surface the body defines a substantially linear through - bore for receiving an end of a spacer member . the through - bore extends continuously through the body in a direction substantially parallel with the substantially planar major surface of the body . the through - bore extends between a pair of end faces which , at least in part , are non - parallel end faces and the body further defines a screw - threaded aperture which extends through the body to intersect and communicate with the through - bore . the body may have a substantially triangular shape in transverse cross - section .