Silva Ranger (old ones) were what I used in my Forest Service career. I always carried a small Silva as a back-up. Came in handy once when on a cloudy day in thick forest I felt my internal compass was correct and the Ranger had to be wrong; but the small back up confirmed it was me that was broken blush - not the compass.

I have had more than one Silva Ranger go defective so a small spare compass was always carried. This is even when using GPS units. Carried two identical Garmin E-Trex units also and one was always more accurate than the other.

Even the best equipment can fail and a spare compass is small and light enough not to be a burden and can prove invaluable.

"It is wise, though, to remember above all else: rifle, caliber, scope, and even bullets notwithstanding, the most important feature of successful big game hunting is to put that bullet in the correct place, the first time!" John Jobson