GEM BIJOU - the Longines Pulsometer Chronograph, a reissue of a watch once used by medical professionals to test a patient's heart rate. The design is based on a watch from the
Hands-On Review - Van Der Gang Original Calendar Chronograph Ref. 20052 (Specs & Price)
Longines Medical Chronograph Pocket watch open face 55 mm. in diameter | eBay