What distinguishes a convertible watch from standard watches?

A convertible watch is specifically designed to change its casing style, transitioning between a hunting case and an open-face design. The hunting case typically has a protective cover that shields the watch face, while the open-face design displays the watch face prominently without any cover. This versatility in appearance and functionality is the hallmark of convertible watches, making them unique compared to standard watches, which typically have a fixed design.

In contrast, the other features mentioned do not define a convertible watch. For instance, a gold case is a material choice rather than a functional characteristic relevant to convertibility. Similarly, double rollers pertain to mechanical enhancements within the watch movement and do not relate to the convertible aspect. A decorative strap affects the aesthetic appeal but does not alter the fundamental design characteristics that define a convertible watch.