Here is an all original seamed E1 handset. The postwar effort devolped the first standard handset and that result was the E1. This handset was first produced in late 1926, and these units were equipped with the "dome" transmitter. The E1 handset is made of Bakelite, a phenol plastic first synthesized in 1907. bakelite is heat resisitant and also resisits most ordinary solvents.