Warning sign with two Boertel hinges worked into the two connected parts to enable folding of the sign

摘要

The foldable warning sign has two separate parts (1,2) which are joined together by Boertel hinges (3,4) which are actually formed in the respective parts of the sign. The sign parts are closed together by folding about the hinges. The hinges may be formed by one side of the sign having slots and the other side having hooks.