The model 12 Twinsonic was the first fully enclosed light bar offered to the public. This light bar took the idea of the visibar and placed the outer rotators under a large polycarbonate lens offered in different colors. The model 12 has 2 full height triple step reflecting cascade mirrors which both face forward. The motor is mounted on the drivers side.
This Twinsonic is a model 12 with dual motors. Photo's courtesy of Eric6913