A safety hand grip for handlebar operated vehicles utilizes an elongate pressure switch in the form of an elongated strip embedded longitudinally within the wall of the resilient hand grip to actuate the horn. Also disclosed are methods of making and using the linkers and supports. The vacuum head is then relocated to the imaging region carrying with it the media. The system further comprises an electron deflection field generating means 380,480,580 arranged to generate a deflection field upstream of the sample surface. The over-centre profile of the cam surface is such that movement of the slider in one direction causes the plunger to be depressed and then released. The invention is characterized by a belt pair in which two belts are connected together in a form-fit andor force-fit and material fit connection, where the belts have a complementary shape in a joining area.