Valve Seat Cutters

valve seat
The non-moving part of a valve. Water flow is stopped when the moveable portion of the valve comes in contact with the valve seat.
Surface against which a valve contacts. Usually, a valve at rest is against the inner seat, and a valve that is actuated is against the outer seat.
The valve seat in an internal combustion gasoline or diesel engine is the surface against which an intake or an exhaust valve rests during the portion of the engine operating cycle when that valve is closed.

cutters
(cutter) someone whose work is cutting (as e.g. cutting cloth for garments)
(cutter) tender: a boat for communication between ship and shore
A person who cuts or edits movies
A tool for cutting something, esp. one intended for cutting a particular thing or for producing a particular shape
A person or thing that cuts something, in particular
(cutter) stonecutter: someone who cuts or carves stone