Swiss made open face pocket timer marked as a Chesterfield 1/5 and in working condition. Also marked antimagnetic. Comes with its original box. But the style number on the box is so worn it is impossible to read. Standard wind-up and marked base metal on the bottom. Chrome plated with almost unseen age deterioration around the edges of the face. With no notches or other indication, it appears to be a screw-back that refuses to cooperate and open to offer additional information. Other identical timers are listed as having 7 jewels. Measures nearly 2-inches.