While standard button compass are 20mm, this 14mm gives you greater hideability. Basic 4 direction compass, and list most button compass you'll want to shake it gently several times to see which way it points north most often.

Tested on Dartmoor, England in late winter. Accurate. Smooth movement of compass card in fluid. No bubbles formed in the fluid, even in cold conditions. The luminous markers work well and gave a clear and unambiguous indication of direction in darkness. Overall, an excellent and inexpensive SERE compass.

You will be hard pressed to find one smaller and more accurate, tested in the jungles of south east asia against bigger suunto units and found superb.