The Hamilton Regulus I is an early electric being released in 1958 and for only one year. As a result, estimated production is only 2,400 and it is, therefore, very hard to find today. It was only ever produced with the 500 movement and is unusual both in its asymmetrical shape and its stainless steel case.
The Regulus II is very different from the Regulus I. It appeared in 1962 with a 505 movement and a standard all stainless steel round case. The dial markers are very unusual and this model is rarely seen, even less than the Regulus I.