The Slim Line I Low Profile Clamping System makes clamping difficult items fast and easy for smaller designs such as pockets of tote bags, computer cases, and backpacks. Choose the window options that best fit your work and add additional windows when needed. Windows are available separately and include the following sizes: 2.5" x 4", 3.5" x 5.5", 4.5" x 4.5", 5.5" Round Window, 5.5" x 3.5", and 6.5" x 5". You will also need to order the Adapter Plate that is specific to your machine (see options below) PLUS the Slim Line I chassis. Adapter plates attached to chassis.