When you ride a lot eventually your screws get lost or stripped and if you are missing or have duff ones, the connection between you and your board is sloppy and less responsive. Don't get caught out at the mountain where they always charge the earth. With this kit you get 8 14mm screw and 8 countersunk washers.  They sit flat and disperse the force far better than screws alone.  The screws come with loctite threadlock. This size fits virtually all boards and binding combos and is all you need.