A semi-trailer anti-theft device or apparatus is provided in the form of a shield which extends over and substantially encloses both the latch handle on the cargo door of a semi-trailer and the padlock associated with the latch. The shield includes an elongated front panel which extends across the...http://www.google.es/patents/US5737946?utm_source=gb-gplus-sharePatente US5737946 - Semi-trailer anti-theft device
