Popular with roadies, combined shifters and brake levers came to mountain bikes with Shimano’s last XTR incarnation.
In essence, you pull these towards the bar to brake, or pivot them up and down to change gear. They do work with Shimano’s customary slickness, although you may ﬁnd the throw on the front shift too long.
However, they’re big, clumpy things, and you’re committing yourself to Shimano brake callipers too. You also risk accidental shifts when the going gets nadgery.