The RMS (root mean square) power is expressed in watts and describes the actual intensity of the subwoofer.

2. A subwoofer up to 200W is recommended for a room up to 20 square meters, while those from 200W to 500W are suitable for larger spaces up to 50 square meters (e.g. living room).

Active

They contain an amplifier inside the speaker. They are also called "active".