A set of 22 compression moulded phenol formaldehyde stair carpet clips. Each clip comprises two parts: one section is for fixing to the stair riser and is drilled to accommodate a screw, whilst the second larger part slots into it trapping the carpet in place. The design was patented in 1932 and was in production in various finishes by 1934. This object was featured in the Ten Most Wanted research project: http://www.10most.org.uk/artefact/stair-carpet-clips
where additional information relating to it can be found.