Mechanical locking system for floor panels

A set of essentially identical floor panels provided with a mechanical locking system comprising a flexible tongue, which is arranged in a displacement groove at a first edge of a first panel, and a tongue groove at a second edge of an adjacent second panel, the flexible tongue is configured to cooperate with the tongue groove for locking of the first and the second edge in a vertical direction,

• wherein:
• the flexible tongue comprises a sliding surface and a locking surface,
• the displacement groove comprises at least two cavities, each comprising upper, inner and lower cavity walls and a horizontal opening, wherein a portion of the displacement groove provided between said at least two cavities is configured to cooperate with a portion of the flexible tongue during locking,
• the second floor panel comprises at least two protrusions, each comprising a sliding edge which is configured to cooperate with the sliding surface during locking and to press and bend a flexible tongue section into the at least two cavities, and
• the flexible tongue section is configured to move back outwardly in a final stage of the locking such that the locking surface is inserted into the tongue groove.