A valved wind instrument including: a tubular body having a tuning section, a lead pipe connected to a first end of the tuning section and a bell pipe connected to a second end of the tuning section, said tubular body being configured to allow a vibrating column of air to pass therethrough; a key assembly; a valve operable by said key assembly for movement of said valve relative to the tuning section between at least one of a first configuration and a second configuration to selectably vary a length of the tubular body through which the vibrating column of air passes when arranged in the first and second configurations and thereby selectably vary an output pitch of the valved wind instrument; wherein the valve and the tuning section each include a respective planar surface that are configured to lie flat against each other or flat against an intermediary planar layer as the valve is moved relative to the tuning section between the first configuration and the second configuration and whereby air ingress and air egress openings of air passage ways in the valve are disposed in the planar surfaces of the valve and are configured for alignment with openings to air passage ways disposed in the planar surface of the tuning section in varying configurations as the valve is rotated relative to the tuning section between the first configuration and the second configuration so as to selectably vary the length of the tubular body through which the vibrating column of air passes when arranged in the first and second configurations; characterized in that at least three intermediate planar layers are disposed between the planar surfaces of the valve and of the tuning section, said three intermediate planar layers including a first and second intermediate planar layers formed from a PTFE material disposed adjacent the planar surfaces of the valve and the tuning section, and a third intermediate planar layer disposed between the first and second intermediate planar layers, said third intermediate planar layer including a sealing gasket layer formed from an elastomeric material. a tubular body having a tuning section, a lead pipe connected to a first end of the tuning section and a bell pipe connected to a second end of the tuning section, said tubular body being configured to allow a vibrating column of air to pass therethrough; a key assembly; a valve operable by said key assembly for movement of said valve relative to the tuning section between at least one of a first configuration and a second configuration to selectably vary a length of the tubular body through which the vibrating column of air passes when arranged in the first and second configurations and thereby selectably vary an output pitch of the valved wind instrument; wherein the valve and the tuning section each include a respective planar surface that are configured to lie flat against each other or flat against an intermediary planar layer as the valve is moved relative to the tuning section between the first configuration and the second configuration and whereby air ingress and air egress openings of air passage ways in the valve are disposed in the planar surfaces of the valve and are configured for alignment with openings to air passage ways disposed in the planar surface of the tuning section in varying configurations as the valve is rotated relative to the tuning section between the first configuration and the second configuration so as to selectably vary the length of the tubular body through which the vibrating column of air passes when arranged in the first and second configurations; characterized in that at least three intermediate planar layers are disposed between the planar surfaces of the valve and of the tuning section, said three intermediate planar layers including a first and second intermediate planar layers formed from a PTFE material disposed adjacent the planar surfaces of the valve and the tuning section, and a third intermediate planar layer disposed between the first and second intermediate planar layers, said third intermediate planar layer including a sealing gasket layer formed from an elastomeric material.