While one watt is plenty for personal use (most small radios that have speakers produce less than1/4 watt) the size is quite small and easy to fit into a case with other projects. Battery operated from 3 to 15 volts; six volts is optimum. You can amplify your other kits; a radio etc. Output into an eight ohm speaker. The PC board is just 1-13/16" square; tallest component about 5/8" tall.