Fulfilled by our friends at Grimworkshop
This Weatherproof plastic tip card, has both a protractor, as well as a ruler attached to it, it's clear design allows you to look through it to judge angles and levels of basic structures compared to the horizon. This card is both waterproof, and U.V. Reisistant, so its perfect to always keep in a wallet. These tip cards are so thin, you can stack dozens together into one wallet slot, or into a small tin.