There's a known issue where the grille foam is missing. This D&B Audiotechnik Ci - SUB 18 subwoofer offers a compact design with powerful bass performance.

To use this subwoofer, simply connect it to your audio system following the standard connection methods. When using, make sure to place it on a stable surface for better sound output. Keep in mind that as the grille foam is missing, be careful of dust getting inside the subwoofer. For maintenance, wipe the exterior regularly with a dry cloth. Avoid exposing it to extreme temperatures and moisture to keep it in good working condition.