Comment by microtonal

The Kinesis Advantage2 and the Moonlander have a piezo speaker to give keystroke sounds. However, they are not for, as you might expect to give the full Mechanical Keyboard Effect™.

If you have mechanical switches, you want to learn to type just past the actuation point and not until the switch bottoms out. This is relatively easy with tactile switches (the have a bump and the actuation point is immediately after the bump). However in linear switches, you don't feel when you have hit the actuation point. So the piezo speaker can be used during the first weeks to train your muscle memory of where the actuation point is, so that you can type lightly.

I had this on my Kinesis Advantage with Cherry Reds, and it was really nice during the initial days/weeks, after which I turned it off.