A SAW device 11 has an IDT which is provided on the principal surface of a quartz crystal substrate 12 having Euler angles and excites a SAW in a stopband upper end mode, and a pair of reflectors which are arranged on both sides of the IDT. The rollver is adapted to roll to a target destination at least partially in response to at least one of an initial impetus imparted to the vehicle and gravitational forces acting thereon, and due to its relatively low cost, can be simultaneously deployed and used in an area of interest in relatively large numbers. , autoimmune diseases, susceptibility to which is determined by expression of particular class II MHC genes. An embodiment of the invention relates to a pyrotechnically activated valve incorporating such features to minimize free play in conjunction with such features so as to restrain the piston and also allow the piston to gain momentum. The identified print defect is removed from the difference image.