A press block is engaged against the gasket to fully enclose an active volume between the press block, the peripheral walls of {HEAD ~ the central opening} in the gasket, and the active surface of {TAIL ~ the substrate} 
A press block is engaged against the gasket to fully enclose an active volume between the press block , the peripheral walls of { HEAD ~ the central opening } in the gasket , and the active surface of { TAIL ~ the substrate }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL