A system for non-contact measurement of thickness of a test object. The metallic coating consists of 1. The spacer is formed following the first etch through the free layer which stops on the barrier layer. When the mounting frame is in its non-working position, gravity holds the conveyor in a position rotated against the other of the stops, the crop-receiving surface then being almost vertical so that the grouper is almost within the length of the mower-conditioner.