If you are interested in optimum keyboard ergnometics, I highly recommend the humanscale keyboard arm. Its got a combined height and tilt mechanism that is adjusted by simply grabbing the keyboard and moving it. The whole thing slides up under the desk to completely disappear. My wife and I share a desk. She is 5'1" and I am 5'11". This arm allows us to set the keyboard for our own fit without having to mess with a bunch of screw type locking mechnisms.
The ergonmetics is far superior to any kind of sliding drawer mechanism and helps with preventing carpal tunnel syndrome. It bolts under any desktop with six screws.
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