This is a mid 1970’s version of the Shimano Lark-W. The W designation indicates that the derailleur has no spring in the parallelogram and is controlled by two cables, pulling in opposite directions, worked by a twist-grip. In the case of this gear, the cable nipples (like a modern brake cable pear nipple) are at the derailleur end, and the clamp bolts are in the twist-grip control.
The Lark and Skylark series began as premium products, but by the mid 1970’s had become budget items. This one lacks the ‘character’ of some of the earlier versions.
I have an indelible memory of trying to set one of these up on a strange orange coloured Puch ladies bike in about 1977 - and giving up and using a SunTour Honor and SunTour Mighty Shift thumbshifter. This was the only brush with Shimano’s W system that I can remember - and it was not a pleasurable experience.
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