It is the "thickness" of the cable. The thicker it is, the more current it can handle without its temperature rising.

3 x 1

Useful for medium-power devices, such as kettles, irons, or small kitchen appliances. It can safely power room lighting fixtures.

The maximum electrical load that the extension reel can support without overheating. This applies only when the extension reel is fully unwound. When it is wound, the allowable power is lower due to overheating.

The cable automatically retracts back into the reel with a "click", just like with a vacuum cleaner.

Single-phase

The single-phase extension reel connects to a household or professional 230V AC supply. It is intended for low or medium power devices, such as lamps, computers, or tools. The operating current usually ranges between 10–16A. It is easy to use and transport, but cannot power high-power machines. It is recommended to use cables of suitable cross-section to avoid overheating.