SAS Survival Button Compass
What I like about this compass other than its rugged construction, is that its dry and will not freeze or develop bubbles on you like many other compasses. I chose this compass for my Personal Survival kit. One problem I will note is they have no attachment points. Being 15mm about 1/2" it could be lost fairly easily. My remedy to that is I have it in a small plastic bag in my Personal Survival kit.
The luminous dots are excellent with a quick blast of a flashlight. 2 dots for north and 1 dot for south. I've read it works quite well in both North and South hemispheres which is a problem with other button compasses. The operating temperature is -40C to +55C which is an extreme tempature range.
NSN #6605 99 522 0223. It's a little steep for a button compass. Coming in just at $35-$40. I believe its worth every dime and would bet my life on it.