Optional volume control, specifically designed for these speakers, which requires no drilling or soldering, is available separately ( ; 425-4548 425-4548 ). Wall Mounted Cabinet Speaker. Furniture quality, incorporating the latest safety features with integral restraining devices supporting them should they be damaged or dislodged. 100V line operation Impedance: 8 Designed for speech and background music in offices and similar environments Profiled edged cabinets Inlaid baffle cloths matching the colour of the cabinet MDF board construction User friendly self-adjusting brackets with safety restrainer Safety guard on 100V line terminal block Five power tappings; 0.125 to 4W, and 0.5 to 8W