Hi Mike,
This from the Microair website might help.
SL30 Interface
Internal vox intercom with auxillary audio (music) automatic mute
Dual Monitoring (Active/Standby)
Selectable Carrier Detect (PTT) - Lockout (saftey feature)
99 programmable memories
Priority Key
larger knobs
Alpha /Numeric Display
5 watts RF carrier output
Memory Sort by Name
Receiver tuning down to 108 Mhz.
2 Year Warranty as standard
Australian Manufactured
All this fits in a 57 mm (2 1/4'') instrument hole and weighing in at 416g (14.67oz).