Fox Shox 38 Air Shaft Assembly Service Kit Replacement Parts Whether you're replacing a broken part or something that's worn out, you'll want to use genuine replacement parts. The Fox Shox 38 Air Shaft Assembly Service Kit is designed for the Fox 38 suspension forks. If you're looking to adjust the travel on your 2021 38mm fork, you must replace the entire Air Shaft Assembly with inner air sleeve. Features Designed for 2021 Fox 38 suspension forks Comes in multiple lengths so you can adjust the travel | Fox Racing Shox | 38 Air Shaft Assembly Service Kit 2021 Float 38 160Mm