Fares are payable using Clipper card or refillable paper-plastic-composite tickets, on which fares are stored via a magnetic strip, to enter and exit the system. Paper tickets are slowly being phased out, and a 50-cent surcharge per trip is applied to all journeys made on paper tickets. The exit faregate prints the remaining balance on the ticket each time the passenger exits the station. A Clipper card or paper ticket can be refilled at a ticket machine, the remaining balance on any ticket can be applied towards the purchase of a new one, or a card is captured by the exit gate when the balance reaches zero; multiple low value cards can be combined to create a larger value card but only at specific ticket exchange locations, at some BART stations. The magnetic strip-based technology was developed by Cubic Transportation Systems with a contract awarded in 1974.