Floor panels are shown, which are provided with a mechanical locking system comprising a tongue with rocker arms that allows locking by a vertical turning motion. The tongue has an inner part mounted in a sideward open fixation groove in a first edge and an outer part extending beyond a vertical plane, the inner part is fixed in the sideward open groove, wherein the tongue has at least one rocker arm extending in the length direction of the tongue, the rocker arm having a displaceable pressing protrusion that during locking is in contact with a second edge and a displaceable locking protrusion that in locked position cooperates with a tongue groove, wherein the locking protrusions are displaced outwardly away from the main tongue body when the pressing protrusion is pressed and displaced inwardly towards the inner part of the tongue.