BC Series 8 inch assembly with 15WFully contained speaker assembly includes 8 inch 15W driver, 25 70V transformer, white grille and conically shaped backbox with clamps for fast mounting to beams or girders. The ready to install speaker package has an outside diameter of 12. 875 inches. Externally accessible speaker leads exit through a metal strain relief clamp. Model No. Speaker Transformer Grille Backbox BC810 72 8 in. 15W dual cone (810) 70 25V (TLM 572) White (WB8) 10 in. dia.