All

The DHX/Float X does have a check valve built in to the underside of the piston bolt- there is a shim under there (drawn in blue) that allows flow on rebound but closes on compression. I think its more common on shocks like Fox and Rockshox because they usually have a wide range of rebound adjustment, so if there was a lot of free bleed there would be a noticeable effect on the compression. Something like the Elevensix has evolved to not use a check valve (which is used to) because the rebound circuit is smaller and has very little...