Inflatables come in various sizes, commonly four feet or 1.2 meters tall (operated with a low-voltage DC power supply and a computer fan), and six or eight feet (1.8 to 2.4 meters) tall, running directly from AC mains electricity. Like inflatable rides, outdoor types are staked to the ground with guy wires (usually synthetic rope or flat straps) to keep them upright in the wind, though being rather flimsy this does not always work. Heavy snow or rainwater which has accumulated may also prevent proper inflation.