- Tile bridge and backbox for mounting ceiling speakers and speaker strobes to drop ceilings. 8 and 4 tile bridge models and 8 speaker back box available.- SSB-8 use with: ST-C8, ST-C8V, ST-C8M, ST-C8VM, S8-70/25, S8-24MCC, S8-24MCCH, Series E90, Series ET90