With all other small keychain or zipper pull compasses, you're just eyeballing or roughly guesstimating when making declination adjustments - which can cause errors of 2 or 3 degrees or even 5 or more degrees (and then you're lucky if they ever find your body). Single degree markers don't appear on keychain or zipper pull compasses. (At least I can't see them with my eyes, and I'm near sighted to a fault). Much easier just to eliminate that issue entirely on my projects where time is of the essence and/or there are immense safety concerns and particularly in remote, hostile areas and where capability, language or translation barriers run rampant for starters. All we need and all we want is a simple small rugged high quality compass with one big, clown-sized arrow (did I say big arrow and universally simplistic?) that always points in a single (one) direction, that being true north. Of course my clients use the most sophisticated cutting edge engineering and geophysical programs with ultra-high resolution imagery during other project phases, but there is a consensus among the geophysicists and engineers that understand my responsibilities, that the Tru-Nord compass is the one. Door step delivery doesn't register as an issue. In regard to direction and distance, I wear lots of hats. But I do more than my share of coordinate system troubleshooting for others. I presently use ArcInfo (formerly used GeoMedia - and I stated out in MicroStation during the civil war). My systems are loaded or are streaming with practically every conceivable type of geo-referenced raster and vector surface and subsurface data imaginable (i.e. that's out there) for reference and contrast, whether proprietary or acquired through public sources. My people are generally the first in. I agree that it's ironic that we use such a low tech tool for such critically important work in one of the most high tech environments of them all. Restated: If you need a zipper pull compass, and care about your employees, I recommend the factory compensated Tru-Nord 150C zipper pull one.