A set of panels comprising a first panel and a second panel , wherein the first panel comprises a first edge , a first panel surface and a second opposite panel surface and the second panel comprises a second edge , a third panel surface and an opposite fourth panel surface , wherein the first edge comprises a locking strip with a locking element configured to cooperate with a locking groove at the second edge of the second panel for locking the first edge to the second edge in a first direction which is parallel to the first panel surface , wherein the first edge is configured to be assembled to the second edge by a displacement of the second edge relative the first edge in an assembly direction , which is perpendicular to the first panel surface , to obtain a locked position of the first edge and the second edge , wherein the locking element comprises a first locking surface at a first angle from a plane parallel to the first panel surface and the locking groove comprises a second locking surface at a second angle from a plane parallel to the third panel surface , that the first angle is different from the second angle such that the first locking surface converges towards the second locking surface at a cooperation part in the locked position, and that the first locking surface cooperates with the second locking surface at the cooperation part for the locking in the first direction , characterized in that the difference between the first angle and the second angle is in the range of about 5° to about 15°, or in the range of about 5° to about 10°, or about 7, and that the cooperation part is positioned at a first distance from a strip surface of the locking strip , wherein an outer surface of the locking element is positioned at a second distance from the strip surface of the locking strip , and wherein a ratio between the first distance and the second distance is in the range of about 0.03 to about 0.3, or in the range of about 0.1 to about 0.2, 03, or about 0.15, whereby the cooperation part is closer to the strip surface of the locking strip than to the outer surface of the locking element . wherein the first edge comprises a locking strip with a locking element configured to cooperate with a locking groove at the second edge of the second panel for locking the first edge to the second edge in a first direction which is parallel to the first panel surface , wherein the first edge is configured to be assembled to the second edge by a displacement of the second edge relative the first edge in an assembly direction , which is perpendicular to the first panel surface , to obtain a locked position of the first edge and the second edge , wherein the locking element comprises a first locking surface at a first angle from a plane parallel to the first panel surface and the locking groove comprises a second locking surface at a second angle from a plane parallel to the third panel surface , that the first angle is different from the second angle such that the first locking surface converges towards the second locking surface at a cooperation part in the locked position, and that the first locking surface cooperates with the second locking surface at the cooperation part for the locking in the first direction , characterized in that the difference between the first angle and the second angle is in the range of about 5° to about 15°, or in the range of about 5° to about 10°, or about 7, and that the cooperation part is positioned at a first distance from a strip surface of the locking strip , wherein an outer surface of the locking element is positioned at a second distance from the strip surface of the locking strip , and wherein a ratio between the first distance and the second distance is in the range of about 0.03 to about 0.3, or in the range of about 0.1 to about 0.2, 03, or about 0.15, whereby the cooperation part is closer to the strip surface of the locking strip than to the outer surface of the locking element . <EOS>