.. do they work well? Any recommendations?
My cycling habit has grown a new pastime, in which I notice features in the distance - a distinctive hill, a tower perhaps - then I try to work out what it is when I return home, using Google Earth or Maps. I have a relatively inexpensive compass acquired recently from Amazon that I've used for this, but the results can be a bit variable - it's difficult to know if you're holding it level when you're squinting through it and if you aren't, the compass wheel can stick.
Any advice welcome, thanks.