3" x 2.77" (7.62cm x  7.04cm) Holographic Green Mechbox Switch Sticker.

The switch is green with a blue stem. The product image includes the "rainbow" affect made by the holographic finish. 

 In the photos I have compared it to the size of a switch, and to the size of the two other stickers I sell in this design. You will of course just receive the 3" sticker (the medium sized one).