Windscreen wiper device

A wiper assembly, comprising:

• an oscillating arm;
• and
• an elongated wiper blade of a flexible material, which can be placed in abutment with a windscreen to be wiped, which wiper blade includes at least one longitudinal groove, in which groove a longitudinal strip of a carrier element is disposed, which wiper blade comprises a connecting device for an oscillating arm, wherein said connecting device comprises at least two opposing spaced-apart sidewalls each comprising a protrusion extending sidewardly and, wherein said connecting device can be connected to said oscillating arm by said protrusions pivotally and snappingly engaging into correspondingly shaped recesses of said oscillating arm, wherein said connecting device comprises a guiding groove defined between said sidewalls and a bottom thereof and the guiding groove separating the protrusions and being arranged for receiving a downwardly extending guiding tongue of the oscillating arm, and wherein said connecting device has an asymmetric form with respect to a middle transverse plane of said connecting device, seen in vertical direction, and wherein a transverse rib is provided in said guiding groove and extends upwardly from the bottom in order to ensure that said wiper blade can only be mounted on said oscillating arm in a predetermined orientation of said wiper blade relative to the oscillating arm, and wherein said oscillating arm has a U-shaped cross-section, and wherein said guiding tongue extends downwardly from a base of said U-shaped cross-section, and wherein said guiding tongue occupies space in said guiding groove that is co-axial with said protrusions when said oscillating arm is attached with said connecting device.