This d&b audiotechnik Ci-SUB 18 Compact Bass-Reflex Passive Subwoofer offers great audio performance. However, it has a known issue: the grille foam is missing.

To use this subwoofer, simply connect it to your audio system following the standard connection procedures. When placing it, make sure it's on a stable surface for optimal sound output. Keep in mind that the grille foam is missing, so be careful to avoid getting dust or small objects inside. For maintenance, you can gently wipe the exterior with a soft, dry cloth regularly. Don't expose it to extreme temperatures or high humidity as it can affect its performance.