Pocket watch compasses can be described as any compass that has an attached lid and are no larger than a pocket watch. Probably at their most popular in the first half of the 20th century. There were models available earlier but the onset of WWI and the need for small compasses for officers ensured that a lot of WWI Pocket watch compasses were manufactured.
After WWII companies such as Taylor, in America, produced many different designs which are very useable and popular.
Some of the earlier, 19th C pocket watch style compasses are quite attractive and easy to carry.
But they could also be larger.