The K-Stock is an electric multiple unit that operates on the MTR rapid transit railway system in Hong Kong.There are two variants: those delivered for the Tseung Kwan O Line now (but from 2002-2009 used on the Kwun Tong Line), and those delivered in 2006 to 2007 for the Tung Chung Line. In 2003 and 2004, these trains (Kwun Tong Line stock) ran on Tsuen Wan Line, Island Line and Tseung Kwan O Line.