Mechanical locking system for building panels

A set of panels comprising a first and a second panel, an edge of the second panel is essentially perpendicularly insertable into a groove of the first panel to obtain a mechanical connection between the first and the second panel, the second panel being displaceable essentially perpendicularly to the first panel, wherein:

• the edge comprises a separate and flexible tongue and the groove comprises a tongue groove, or the edge comprises a tongue groove and the groove comprises a separate and flexible tongue;
• the separate and flexible tongue is insertable into the tongue groove for connecting the panels to each other in a first direction, which is perpendicular to a main plane of the first panel;
• the edge of the second panel is configured to cooperate with the groove of the first panel for connecting the panels to each other in a second direction, which is parallel to a main plane of the first panel;
• the length direction of the separate and flexible tongue extends parallel with at least one of the edge and the groove;
• the groove comprises an opening, two side walls and a bottom;
• the separate and flexible tongue is arranged in an insertion groove;
• the separate and flexible tongue has an inner part mounted in the insertion groove and an outer part extending outside an opening of the insertion groove;
• and
• the separate and flexible tongue is displaceable inwardly towards a bottom of the insertion groove and outwardly into the tongue groove during locking.