A locking system for floor boards comprises a plurality of floor boards and a plurality of locking devices. Each floor board has two tongues on one lateral side and another tongue and a locking groove on the opposite lateral side. The floor board also has two grooves on its bottom side. The locking device has three protruding gripping extensions. Few locking devices are placed on each floor board before the floor boards are sent to a job site. At the job site, two adjacent floor boards are assembled together by inserting the tongue of one board into a space defined by the locking device and the tongues of the adjacent board. The tongues are further secured in place by compression of flexible buffers located at each protruding gripping extension.