Caddies plug into a Mini or Maxi Surface to keep cutters and pens handy. One helpful function of the Caddy is how you can use it as a cap for your "Sharpie" pen when you are making pattern lines on your glass. As you know it takes two hands to remove your "Sharpie" cap and you usually only have one hand free. The Daddy replaces the cap, it is easy to find and remove when marking your glass. Note: Replace the cap when your done to prevent the pen from drying out.