Just a guess, 'Mid Band' might refer to the 72 MHz region.
Found one on EBay with some info:
Nady Wireless 121
Bronze Series
Mid Band Receiver
Channel MB3
85.275 MHz
Nady 121 Single Antenna VHF Wireless Receiver
So, 72-210 MHz, more or less. 85 would be in a TV channel.
Ah, found a table of channels/designators from NADY:
Digital and Analog Television interference with VHF systems 10/11/2004
This product operates between 72-87 MHZ and 170-234 MHz
TV CH / Freq MHz / VHF Frequency Designator
None -----72.300 MHz BB
None -----72.500 MHz CC
None -----72.700 MHz DD
None -----72.900 MHz EE
None -----75.500 MHz FF
None -----75.700 MHz GG
None -----75.900 MHz HH
None -----81.350 MHz MB1
TV 6 -----83.880 MHz MB2
TV 6 ------85.275 MHz MB3
TV 6 ------87.375 MHz MB4
None -----170.245 MHz G1
None -----171.905 MHz A
None -----173.800 MHz E4
None -----174.100 MHz E5
TV 7 ------174.500 MHz E6
TV 7 ------175.000 MHz E3
TV 7 ------175.550 MHz CE6
TV 7 ------176.400 MHz CE7
TV 7 ------176.900 MHz A14
TV 8 ------183.570 MHz CE9
TV 8 ------185.150 MHz B
TV 8 ------185.250 MHz CE1
TV 9 ------191.300 MHz H
TV 10 ----195.250 MHz CE2
TV 10 ----197.150 MHz N
TV 11 ----202.100 MHz A1
TV 11 ----203.250 MHz CE3
TV 11 ----203.400 MHz F
TV 12 ----206.350 MHz P
TV 12 ----209.150 MHz D