This Bridgestone Klimatic was a tidied up child of the Bridgestone SMS Max. (both were manufactured by SunTour). The indexing cylinder below the derailleur has become a fraction of the size, although it still turns a cam that drives a roller that drives the parallelogram in the same basic way. The pulley cage still has a large (although not quite so huge) offset. Plastics have been used to keep the cost and weight down. All very good, but by this time Shimano had established SIS and no one (except Bridgestone) was interested in SunTour’s cam based system. I believe that SunTour manufactured the Klimatic range exclusively for Bridgestone.
Interestingly the indexing mechanism means that the adjustment screws have been moved to the front of the derailleur (as on the original SunTour Competition). Long ago this design was abandoned because the screws tended to catch spray from the front wheel and rust solid - but this would not be a problem with plastic.