X2. I have used the All Balls conversion for my 90 YZ250 to 2017 KYB SSS forks & Clamps from a YZ250F and the 2016 SFF forks from a CRF450R that I am putting on my 89 CR250. My son is also finishing up his CRF450R SFF forks on his 89 CR250 as well using the All Balls kits.