On a flexible substrate is printed, LEDs, a battery, a flasher, and an actuator. The actuator may be a photo-switch that causes the battery and flasher to periodically energize the LEDs when a sufficient ambient light impinges on the actuator. The substrate may be an insert in a transparent package containing a product, such as a razor. When the package is in the front of a display in a store, the ambient light causes the LEDs to flash, such as every 10-30 seconds to attract consumers to the product. The substrate may also form part of the outer surface of the package. The flasher may simply flash the LEDs or create a dynamic display by energizing different groups of the LEDs at different times.