Abstract: An envelope for a rod serving to lock the position of a motorcar seat is formed by two half shells made of stamped plate and separate from one another. For one end of the half shells there are provided means for the mutual coupling and engagement of the rod on the stationary part of the seat. On the wall of one of the half shells a protuberance containing an attachment hole is provided. The attachment hole allows fixing a cable to respective control tab which, in its turn, operatively swings into a suitable cavity formed on the other half shell.