Abstract: Disclosed is a device disposed in one of a plurality of holes on a body of a surfboard for fixing one of a plurality of fins therein, each fin including an elongated tab extended downwardly, horizontally from a base thereof, the tab including a plurality of spaced protrusions on its either side. The device comprises a central, lengthwise slot including a plurality of spaced projections on its either side above its bottom, wherein responsive to inserting the tab into the slot, the tab is adapted to move rearward by snappingly pushing until the tab is stopped by a rear end of the slot with upper surfaces of the protrusions engaged with lower surfaces of the projections. Either assembly of the fins without sacrificing its fastening or disassembly thereof can be made easy.