We manually check that every strut spacer we ship is the proper size for each kit - this should be marked accordingly on your strut spacer box with a sticker. The relationship between the amount of lift gained with a strut spacer is approximately double the size of the strut spacer itself, due to the length and angle of the lower control arm and the position of the strut. Please refer to our blog post here for more information: https://torchoffroad.com/blogs/news/strut-spacer-size-explanation