3.5 × 2.9 mm SMD SPST-NO tactile switch, top-actuated, 3.5 N force, rated 50 mA at 12 VDC.
Also added the official Würth Elektronik datasheet URL. The 4-pad footprint dimensions and pin numbering match the datasheet; pin descriptions are missing and should indicate pins 1/3 common and pins 2/4 common.