going back deep into the memories, my fist derailler bike had those, and as I recall the were not as effective as using the standard levers.
I took them off, in large part to the description of the in "Anybodys bike book" as something to the effect of "phooey, junk, trash" or thereabouts
__________________
Life is too short not to ride the best bike you have, as much as you can.