The Cube Combo includes our classic Battery Cube as the power source for your circuits. It has a positive and a negative terminal. When you turn on the power switch, it delivers approximately 3.7 - 4.2 volts DC to your circuit. Also included is our Geared Motor Cube. This mighty little motor rotates at more than 1,000 RPM (rotations per minute), but the tiny gears attached to the motor shaft reduce the rotations to about 75 RPM. The LED Cube is a bright light, making a perfect searchlight for your vehicle or beacon on top of your lighthouse. An LED is a polarity-sensitive device, which means current only flows in one direction. If the LED does not turn on when you connect the wires to the battery, try reversing the wires to reverse the current flow. Fits your bricks! Works with all LEGO® and MegaBloks®-type construction bricks Seamless circuit connectivity (no soldering) Safety-tested & approved for ages 8+ Created by STEM teachers, tested by kids