Are you looking for vintage, or new? The new vehicle kind uses 2 heavy rubber straps to hold a 5lb, or a 10lb, or a CO2, or 20 lb to a ridgid bracket. The older vehicle type brackets use an over center type lever. Again you have to specify what size, and type of extinguisher you are mounting to your vehicle. It has rubber bumpers that protect your extinguisher. Check out Brooks Fire Equipment on line to see the modern style. They might have different styles by now.
Art (35 years in the fire sprinkler trade and 15 of that servicing extinguishers)