The Jagwire one is for for like thick wall tube carbon fiber time trial bars ..
that grips the outside of the tube.
You still need to buy the Shimano bar ends to get the shifters, so,
in that, is like Paul's 'Thumbies' ,
another aftermarket accessory mount,
for the Owners of Shimano bar end shifters.
might work with friction down-tube levers, or the reproduction ST ones Riv Bike
sells as "silver shifters", since they also make a copy
of the Shimano bar end shifter pod.