The earliest fiberglass Eames chairs were produced by Zenith Plastics and came in a limited palate of 5 colors including lemon yellow. The Zenith produced shells are distinctive for their high fiber content, larger, more substantial rubber shock mounts and translucent fiberglass.
The fiberglass chairs came with a range of bases to accommodate different uses and aesthetics. The DAR was the designation given chairs such as these with wire "Eifel Tower" bases and a seat height perfect for use at a table or desk. 
These chairs are from the "transitional" period when Zenith Plastics was still making the shells, but had stopped imbedding rope around the edge. They have rubber and stainless glides on the feet. Two retain partial red Venice lables.