A connection system for connecting a board 1 to a boot comprises a plate 5 which is connectable to the board 1, a button 3 having a bottom face and a top face, the top face being connectable to a boot or binding 2, and a collar 4, wherein a part of the button 3 is sandwiched between the collar 4 and the plate 5 with its bottom face adjoining the plate 5, and its top face exposed through the collar 4, such that it can rotate about an axis passing through the connection system and wherein the bottom face of the button 3 has a curved surface, which has rotational symmetry with and which adjoins a complimentary curved surface on the plate 5, such that button 3 can roll to move its axis of rotation A away from an axis P perpendicular to the plate 5, and in that the connection system comprises braking means 8, which restricts movement of the button 3.