XRAY have informed that the T4’18 kits shipped until today include the shock absorber silicone O-rings 3×2 (part number #972030) which are slightly too tight. Despite the difference in thickness being very minor and not noticeable by eye, the performance difference is noticeable as the shock shaft does not move as freely as it should.
XRAY strongly recommend not using these silicon O-rings while building the shock absorbers, but rather using the silicone O-rings from previous T4 kits or replacement silicone O-rings which we will provide free of change. They will be ready to ship free replacement O-rings in a very short time.
Read more at: http://bit.ly/2xUiCZ2