This is a 500 KHz auto alarm. MIMCo had done away with the meter which registered the number of 4 second dashes recorded and replaced it with four LEDs. These can be seen on the left half of the panel in the photograph. The Lifeguard III is believed to be the last of its generation.
Lifeguard III photo courtesy Teneo.org
Contributors and Credits:
2) Graham Wright, G4FUJ <graham.wright(at)ukps.ssn.hp.com>