Attribution: By Otis Historical Archives of "National Museum of Health & Medicine" (OTIS Archive 1) [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons
You may need one of these after the zombie apocalypse. If a zombie eats a leg out from under you, you're going to have a tough time standing on a ladder while installing overhead infrastructure.