The Bell Explorer is a dual-wave (described in sales literature as 'world wave') version of the Colt.
This was the only dual-wave colt made, although there was a Fountain dual wave radio that used a Colt chassis.
Bell Colts ran from 1951 through until 1980 - the longest running model of NZ built domestic radio. It saw many different engineering changes over the years, and the last few models dropped valves in favour of new transistor technology. There is considerable information on the main Colt page about this Kiwi icon.
The radios in this series are: