Swiss - Recta DP-10 compass

Recta DP-10: has a prism, and I don't understand why it also has a mirror, except for combing your hair. The match box models always come with their old problem of air bubbles, very annoying in the mountains when you want to measure the direction toward a somewhat higher mountain top: the bubble places itself where you want to read the scale. You can use it directly on the map, although it's not very transparant, the protractor is very small and is of poor visibility. It also has a clinometer, but it is not very precise. You can use it in winter with not too thick gloves.