Reinforcing Accessories include the following components: Connolly Key Joint, which is a galvanised steel tongue-and-groove formwork that becomes part of the slab forming the control joint. Reo-Sok, which has been designed to prevent injury to workers caused by the exposed ends of reinforcing bar. Bar Chairs, a simple plastic component, designed to position reinforcing fabric and bars within the slab. Polythene Film, which provides a moisture and vapour barrier for use on slab on ground constructions.