The invention provides a currency selectable stored value instrument, whose currency may be chosen or converted at the time value is loaded, after load but prior to redemption of value, at the time of redemption, or at other times. The first n-type GaN layer, the connecting layer, and the second n-type GaN layer are formed on the substrate in sequence. An abstract solution is found to the CSP, including a given assignment of the variables in the first set. The crash direction-computing module is coupled to the acceleration-sensing module for receiving the acceleration information therefrom and is configured for determining impact direction information resulting from the vehicle collision event.