Tk Valves

valves
A membranous fold in a hollow organ or tubular structure, such as a blood vessel or the digestive tract, that maintains the flow of the contents in one direction by closing in response to any pressure from reverse flow
(valve) device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone
(valve) control consisting of a mechanical device for controlling the flow of a fluid
A cylindrical mechanism in a brass instrument that, when depressed or turned, admits air into different sections of tubing and so extends the range of available notes
A device for controlling the passage of fluid through a pipe or duct, esp. an automatic device allowing movement in one direction only
(valve) a structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it

tk
.tk is the Internet country code top-level domain (ccTLD) for Tokelau, a territory of New Zealand located in the South Pacific.
Tk is an open source, cross-platform widget toolkit; that is, a library of basic elements for building a graphical user interface (GUI).
TK is a Peruvian rock band formed in 2001 by Emilio Perez de Armas and Edgar Guerra.
Tank
Truck