Abstract: A fastening member, comprising a first extension having a thickness in a first direction, extending in a second direction, and having a length in a third direction; a second extension connected to the first extension and extending in a direction that is reverse to the second direction; and a hole penetrating the fastening member. The fastening member comprises at least one projection, wherein the projection protrudes from the first extension to the first direction or to a direction that is reverse to the first direction. A method for fastening two elements to a support, the method comprising inserting the first extension of the fastening member to a groove of an element; arranging a second element such that another extension of the fastening member becomes arranged into a groove of the second element; and fixing the fastening member to a support using a fixing means such as a screw.