These are 100% copper gaskets used in test cell#1.

The cell is made with conflat type flanges that have a knife edge that digs into these copper gaskets to make an ultra-tight seal.

We have used these on vacuum systems down to to a trillionth of an atmosphere.

Once they have been used, they cannot be used again, though, so we are offering them to you.  Each of these were used on the first test cell which we have needed to open up the most to modify things as we learn.

On one of the gaskets you can see that the copper is discolored on the outer part of the surface.  That is where it was used as the cell got hot and that part of the gasket was exposed to air.