A set of panels including a first panel, a second, and a locking device. The locking device includes an edge groove at the first edge and a tongue groove at the second edge. The edge groove includes a flexible tongue arranged in an insertion groove at a first side of the edge groove. The edge groove includes a first groove surface at a first side of the insertion groove and a second groove surface at a second side of the insertion groove. The second edge includes a first edge surface at a first side of the tongue groove and a second edge surface at a second side of the tongue groove. The locking device is configured to be unlocked by inserting a tool in the tongue groove. The first groove surface is arranged offset in a second direction relative to the second groove surface by a first distance.