Corresponds to what was missing: a keypad to complete my short cute Apple keyboard that I had voluntarily chosen and for purchase. In practice, of course, we realize that using the shift key in the numbers, it's a little swelling. This small pad sober design but ultimately very well integrated into the metal look of Apple compensates this lack. I chose with USB because I think it's easier and safer to install than bluetooth. Therefore immediate installation (something is displayed on the screen but apparently it was useless). Certainly it takes a USB port behind my Mac, but it is not serious. I let a little behind the computer when I do not need and just take the necessary thus clearing the desk. The keys are a bit harsh but ultimately it is not annoying. Keys "clear" and "delete" practices. A little pricey for what it is, however, perhaps ...