Patent ID: 8857126

Claim:
Building panels, including a first building panel and a second building panel, provided with a locking system for vertical locking of the first building panel and the second building panel by a vertical displacement of the first and second building panels relative each other, a displaceable tongue in a sidewardly open displacement groove provided at an edge of the first building panel, said displaceable tongue cooperates with a tongue groove provided at an adjacent edge of the second building panel for locking the edge of the first building panel and the adjacent edge of the second building panel vertically, and a strip that protrudes: below the sidewardly open displacement groove and outwardly beyond an upper part of the edge of the first building panel; or below the tongue groove and outwardly beyond an upper part of the adjacent edge of the second building panel, wherein the displaceable tongue comprises a pulling extension at an outer part of the displaceable tongue and configured to cooperate with a pulling protrusion formed at the adjacent edge of the second building panel such that the displaceable tongue is pulled out from the sidewardly open displacement groove and into the tongue groove when the edge of the first building panel and the edge of the second building panel are displaced vertically against each other.