The XXtra FM Synthesized Receiver is the world s first small size, lightweight, low-power synthesized receiver. This small FM receiver is similar in function to the popular Novak XXL receiver except for one big difference the XXtra does not use a standard receiver crystal. Instead, all it takes to change the frequency channel is a simple twist of the dial. Carrying extra receiver crystals is soon to be a hassle of the past! Based on the world-champion XXL receiver circuitry, the XXtra has additional sophisticated technology, low-voltage operation (3.0 volts DC), and Solid State Reverse Voltage Protection. The XXtra works with all popular radio systems. Optional Slot Cover Included