Hamilton Jazzmaster Open Heart AutovsMarathon JDD (Jumbo Day/Date) Anthracite Diver's Automatic

The Hamilton Jazzmaster Open Heart Auto is noted for its dressy yet versatile design, featuring striking gradient dials and intricately shaped cutouts that reveal the H-10 movement. It boasts an 80-hour power reserve and Nivachron hairspring. The watch is available in 36mm, 40mm, or 42mm stainless steel cases. On balance, the Hamilton Jazzmaster Open Heart Auto is appreciated for its visually engaging dial and movement display at its price point.

Owners widely praise the Marathon JDD (Jumbo Day/Date) Anthracite Diver's Automatic as a tough, underrated tool watch with lifestyle appeal, highlighting its robust build and tritium lume for excellent legibility. However, its 46mm size is a common criticism, with some finding it heavy and top-heavy, and the OEM rubber strap stiff. One owner noted the watch runs about 10 seconds fast after three days, and the ETA 2836-2 movement offers approximately two days of power reserve. On balance, owners and reviewers rate the Marathon JDD (Jumbo Day/Date) Anthracite Diver's Automatic highly for its robust tool-watch build and legibility, despite its substantial size.