These end caps are suitable for E-sync hubs with 6-bolt formats and axle spacings of 142 mm, 148 mm, or 157 mm, along with Shimano Micro Spline freehub bodies. The end cap on the non-drive side includes a low-friction U-seal that clicks in place and stays secure even when your wheel is removed from your bike. Compatible with E-sync, Neo, and Neo Ultimate hubs with 6 bolts and spacings of 142 mm, 148 mm, or 157 mm featuring Shimano Micro Spline freehub bodies. Not compatible with SRAM XD/XDR or Shimano HG freehub bodies. Not compatible with Centerlock hubs. Not compatible with E-sync and Neo hubs with 135 mm or 150 mm spacings. Not compatible with M-pulse hubs.