[Walt Fricke]

Short answer - you can't pick them up locally from a hardware store. A Porsche dealer (though nowadays they'd probably have to order), or a shop which works on Porsches (may have some used ones sitting around - used is just fine). If you happen to live next door to Maryland Metric or some specialty fastener place, maybe they'd have these, but I don't think they are in any way a standard washer. Others have noted features not found in normal washers. The thickness alone puts it in the special class.