The strippenkaart ticket currently in use on Amsterdam city metro, buses and trams will be replaced by a new chip card in early 2007 in a move intended to make using public transport easier and to prevent people riding the system without paying. The new card will eventually be valid on all public transport networks, including trains, throughout Holland. Passengers will be able to top up their card and tourists will be able to purchase pre-paid cards for temporary use. There is no fixed date for the changeover as some technical problems need to be ironed out. Meanwhile, the strippenkaart can be bought at GVB (public transport) sales points, at the train station, post office, Amsterdam tourist office or in tobacco shops. It can also be purchased on board the tram, but this costs more.