A set of panels including a first panel with a first main plane and a second panel with a second main plane. The first and the second panel include a mechanical locking device which is configured for locking a first edge of the first panel to a second edge of the second panel at a junction plane. The first main plane is essentially perpendicular to the second main plane and the junction plane is extending between the first main plane and the second main plane. The mechanical locking device includes at the first edge an edge tongue which extends from the junction plane and at the second edge includes an edge groove at the junction plane. The mechanical locking device includes a dowel at the first edge and a dowel groove at the second edge. The dowel is configured to cooperate with the dowel groove.