This customization option allows you to add 2 to 4 letters to the upper back of a garment. These letters are 4-inch in size and are made of twill fabric. The fabric has a glue backing that is heated into place first on the back so there are no bubbles, and then each layer of letter is sewn down. Please only enter 2-4 letters to be used, if you are looking to add more letters to your back, please call customer service for other options. There are 3 different fonts to choose from. The price is $5.99 for 1 layer of letters and $11.98 for letters with a top color and a border color.