A timing belt kit or set consists of the timing belt as well as the tensioner pulleys.
The timing belt synchronises the combustion process in your car. It does so by turning the camshaft thereby ensuring that the valves in your engine open and close at the right time. In addition the timing belt turns the water pump in your engine. At Mister-Auto.co.uk we therefore recommend you replace your timing belt and water pump at the same time.