Is they are simply adjustable what makes you think it will change the height? I had cyclecat ones a few years ago, inch lift plus adjustable, they were great but had to flip the throttle (916) Just fitted some cheap adj with inch height to gixer...on these you get what you pay for
I have 2 sets of Gilles bars for my projects - they don't adjust in height and I don't think they are higher than standard bars looking at them. You can spend more and get risers as the picture I posted earlier.
Its the angle that adjusts rather than the height if that makes sense, though i guess you could make the bars flat as a result.
I've got some just like that for less than £50 and they are trick and adjustable but if you fall off they are too weak so can get wrecked!