125x125 buttons are used for Entrecard (they won't accept any other sizes, and if you opt for them to design it for you, their designers suck), as well as what you usually see under "sponsors" (for example at johnchow.com under "sponsors"). It doesn't matter what your product is if your design doesn't look good, because if your banner looks unprofessional, no one will click it. I'll design 1 or more buttons for you based on what you need. Here are some samples of my work: Price is $20-50 depending on what you want. Message me if interested!