This spacer kit will reduce any Wheeldock unit by 1-3/8 inch by 1/8 inch increments and consists of 4 spacers with the following thicknesses: 1/8, 1/4, and 2- 1/2 inch spacers. This kit will reduce a model 3 to a model 1 or any size in between. Comes with 2 reusable zip-ties.