Datavideo's TB-5 Tally Box is an accessory for the SE-500 or SE-900 switchers which takes tally commands from the switcher and turns on/off up to four tally lights to indicate "next up" and "live". The tally lights are connected and powered by mini phono plugs. Each TB-5 unit comes packaged with four tally lights, one cable for each light, serial cable to connect to the switcher, and a power adapter. Use two sets of TB-5s for up to 8 tally lights when connected to the SE-900.