Need a Numeric Key Pad to use for quick logins

Hi. I need a clean, easy number keypad to use for quick logins. I do php projects and use JQuery and AJAX a lot. I just want users to be able to enter 4 digits and it submits the code to my login function...which I can do that last part. So upon entry of the 4th digit it should submit the input.

I want something simple with circular buttons like the attached screenshot.