Abstract: The invention relates to a fastener intended for mounting objects on plates, comprising two mutually movable tongues (2, 4), which are pressable against opposite sides of a plate. The two tongues (2, 4) are included in separate parts (1, 3), a first one (1) of which includes two male-like, elastic resilient fingers (5, 5′) having first serrations (6), while the second part (3) comprises a seat (11), which is delimited by second serrations (12). The two fingers (5, 5′) are insertable in the seat (11) to a depth which is determined by the thickness of the plate, the fingers (5, 5′) as a consequence of the inherent elasticity thereof being kept resiliently pressed in the seat with the first serrations (6) in engagement with the second serrations (12) in order to lock the parts in relation to each other.