in this embodiment two springy lips 15 a 15 b are provided which push the fastening clip 1 against the retaining plate 20 in this manner the fastening clip 1 once it has been positioned on the retaining plate 20 is held in position by the pushing force of the springy element 15 opposite the fastening clip 1 in this manner the springy element 15 exercises a pushing force on the fastening clip 1 in a direction which is opposite to the tractive force exercised on the fastening clip 1 by the fixed part 6 of the lower tackle cords 2 the first opening 21 a and the second opening 21 b in the retaining plate 20 are chosen such that the fastening clip cannot be loosened without exercising a vertically downward force on the fastening clip 1 opposite the springy lips 15 a 15 b directed downwards the first opening 21 a is located on the side of the retaining plate 20 and is open on this side this first opening 21 a has a diameter which is smaller than the diameter of the extremity 13 a of the first projection 12 a the opening 21 a has a diameter which is larger than or fitting for the diameter of the second part 14 a the second opening 21 b consists of two partial openings namely a first 22 a and a second partial opening 22 b the first partial opening 22 a having a diameter which is larger than the largest diameter of the second projection 12.