A switchable cam follower of a valve train assembly of an internal combustion engine is proposed, with an external lever that encloses an internal lever with its arms, of which components, that can deviate from each other flexibly, run on an axis that is attached to a valve side end, and the internal lever on an underside on the valve side end possesses a mechanism for a gas exchange valve as well as a complementary surface at the other end for storage on a head of a support element. A special characteristic is that guidance plates for the gas exchange valve come out from the underside of the external lever. That way, the switchable cam follower can be made narrower at least on the valve side. In addition, development of the mechanism for the gas exchange valve on the internal lever is simplified.