A quick-connect coupling for connecting an exchangeable head to a pressing device, wherein a number of balls K1 with a diameter D1 is radially movably disposed in a ball-holding part on the pressing device and wherein a peripheral groove with a groove depth N1 to partially hold the balls K1 is present on a shaft part in an area with a shaft radius R1 with the pressing device and the exchangeable head in a connected state and wherein a locking ring is movably attached to the ball-holding part in an axial direction, the balls K1 being held radially fixed in the peripheral groove by said locking ring when the pressing device and the exchangeable head are in the connected state, and where furthermore - on the shaft section of the exchangeable head in an area with a further shaft radius R2, which is smaller than the shaft radius R1, there is a further peripheral groove with a further groove depth N2 wherein further balls K2 are likewise disposed in a radially movable manner in the ball-holding part and where the further peripheral groove is disposed closer to the pressing device in an axial direction, such that the peripheral groove and the balls K1 and the further peripheral groove and the further balls K2 serve to transmit greater longitudinal forces, characterised in that - the further diameter D2 of the further balls K2 is greater than the diameter D1 of the balls K1 and that furthermore the further peripheral groove and the further balls K2 are dimensioned such that it is impossible to use the exchangeable head if it is wrongly positioned in the pressing device, by dimensioning such that - the diameter D1 of the balls K1 is the same as or smaller than the difference between the diameter D2 of the further balls K2 and the further groove depth N2. - on the shaft section of the exchangeable head in an area with a further shaft radius R2, which is smaller than the shaft radius R1, there is a further peripheral groove with a further groove depth N2 wherein further balls K2 are likewise disposed in a radially movable manner in the ball-holding part and where the further peripheral groove is disposed closer to the pressing device in an axial direction, such that the peripheral groove and the balls K1 and the further peripheral groove and the further balls K2 serve to transmit greater longitudinal forces, characterised in that - the further diameter D2 of the further balls K2 is greater than the diameter D1 of the balls K1 and that furthermore the further peripheral groove and the further balls K2 are dimensioned such that it is impossible to use the exchangeable head if it is wrongly positioned in the pressing device, by dimensioning such that - the diameter D1 of the balls K1 is the same as or smaller than the difference between the diameter D2 of the further balls K2 and the further groove depth N2. - the further diameter D2 of the further balls K2 is greater than the diameter D1 of the balls K1 and that furthermore the further peripheral groove and the further balls K2 are dimensioned such that it is impossible to use the exchangeable head if it is wrongly positioned in the pressing device, by dimensioning such that - the diameter D1 of the balls K1 is the same as or smaller than the difference between the diameter D2 of the further balls K2 and the further groove depth N2.