The whole design is built from the ground-up to be comfortable and to not strain your wrists while looking terrific on your desk.! Form, meet function! I had originally gotten the Arc-touch mouse because of the novelty factor, but I've since fallen in love with it and won't use anything else. I love the responsiveness and simplicity as well as the ability to turn it on and off when I'm not using it, affording me the option to save the batteries. The Sculpt keyboard is/was (probably) designed as a counterpart for the Arc-touch mouse, so I gave it a go and fell in love with it, as well! I love being able to put the number pad wherever I'd like or to just put it in a drawer when not in use, if I so choose. I am proficient with ten-key, so a number pad is important to me when doing large numbers of... numbers, but I don't always want a huge keyboard cluttering up my desk. I don't think I'll ever go back to using a conventional keyboard again, or one with the number pad attached to it.
The Microsoft 1558 key pad is worthless by itself. It does not pair to a Windows computer. It only pairs with a certain Microsoft keyboard. If you’re just looking for a keypad, as I was, move along and look elsewhere.