I gave you the Vesrah thickness number, yamahama. I've used Vesrah gaskets for many years and have measured head gaskets from Yamaha and from Vesrah. Vesrah gaskets can't be distinguished from OE, and I suspect that Vesrah made the originals. Cometic also makes XS650 head gaskets, in fiber or copper. Copper Gaskets Unlimited in Tempe, AZ is another source. If you decide on a copper gasket, be sure to anneal it. The drill I follow is to hang the gasket on a wire and work with two propane torches with spreader tips, one in each hand, to heat the gasket cherry red, then drop the hot gasket into a bucket of cold water to quench.