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Asshole design: the Kungs replaceable blade icescraper
(toobnix.org)
This is a community for designs specifically crafted to make the experience worse for the user. This can be due to greed, apathy, laziness or just downright scumbaggery.
The one I have looks pretty much the same, but one of the edges is straight, one is concave and the last one is serrated. Maybe the concave edge is also designed to work only one way. If so, it makes sense to prevent the user from flipping it over.