A set of decking boards provided with a connecting system comprising a connecting device, the set of decking boards comprising: a first decking board comprising a first side portion and a second decking board comprising a second side portion, each side portion extending along a longitudinal direction of the decking board, wherein each of said first and second side portions (103,104) comprises: a first lip (110, 140) and a second lip (120, 150), wherein an extension of the second lip in a transverse direction of the decking board is larger than an extension of the first lip in said transverse direction of the decking board, wherein the first decking board is configured to be connected to a support element, and wherein the second decking board is configured to assume a vertically locked state with respect to the first decking board, wherein in said vertically locked state: said connecting device engages with an inner wall of the second lip of the first decking board and with an inner wall of the first lip of the second decking board; the first lip of the first decking board and the second lip of the second decking board are provided in a first horizontal plane, and the second lip of the first decking board and the first lip of the second decking board are provided in a second horizontal plane, said first and second horizontal planes each being parallel with a surface member (101, 102) of the first and/or the second decking board; there is a vertical gap between a portion of the second lip of the first decking board and a portion of the second lip of the second decking board; and there is a horizontal space between the first lip of the first decking board and the second lip of the second decking board, wherein the connecting device is configured to cooperate with the support element via an attaching element, the attaching element being configured to be provided through the second lip of the first decking board and through the connecting device, and characterized in that the connecting device comprises a third segment configured to engage with a side wall of the second lip of the first decking board and configured to be pressed into the support element. a first lip (110, 140) and a second lip (120, 150), wherein an extension of the second lip in a transverse direction of the decking board is larger than an extension of the first lip in said transverse direction of the decking board, wherein the first decking board is configured to be connected to a support element, and wherein the second decking board is configured to assume a vertically locked state with respect to the first decking board, wherein in said vertically locked state: said connecting device engages with an inner wall of the second lip of the first decking board and with an inner wall of the first lip of the second decking board; the first lip of the first decking board and the second lip of the second decking board are provided in a first horizontal plane, and the second lip of the first decking board and the first lip of the second decking board are provided in a second horizontal plane, said first and second horizontal planes each being parallel with a surface member (101, 102) of the first and/or the second decking board; there is a vertical gap between a portion of the second lip of the first decking board and a portion of the second lip of the second decking board; and there is a horizontal space between the first lip of the first decking board and the second lip of the second decking board, wherein the connecting device is configured to cooperate with the support element via an attaching element, the attaching element being configured to be provided through the second lip of the first decking board and through the connecting device, and characterized in that the connecting device comprises a third segment configured to engage with a side wall of the second lip of the first decking board and configured to be pressed into the support element. said connecting device engages with an inner wall of the second lip of the first decking board and with an inner wall of the first lip of the second decking board; the first lip of the first decking board and the second lip of the second decking board are provided in a first horizontal plane, and the second lip of the first decking board and the first lip of the second decking board are provided in a second horizontal plane, said first and second horizontal planes each being parallel with a surface member (101, 102) of the first and/or the second decking board; there is a vertical gap between a portion of the second lip of the first decking board and a portion of the second lip of the second decking board; and there is a horizontal space between the first lip of the first decking board and the second lip of the second decking board, wherein the connecting device is configured to cooperate with the support element via an attaching element, the attaching element being configured to be provided through the second lip of the first decking board and through the connecting device, and characterized in that the connecting device comprises a third segment configured to engage with a side wall of the second lip of the first decking board and configured to be pressed into the support element.