Sennheiser EM 3031-U Instructions For Use Manual page 5

Fuse holder and mains voltage selection
2-pin IEC mains connector
Squelch control
Straw relief clamp for mains cable
Service interface (not used in normal operation)
AF output XLR-3, balanced
Control for AF output level at the XLR socket
Antenna input B
Antenna input A
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