Abstract: A contact spring assembly includes a contact spring having a connection part for an electrical conductor and a contact part with a spring leg base and spring legs originating therefrom for contacting a plug contact. A detent sleeve is retained at the spring leg base, produced from sheet metal as a stamped and bent part, surrounds the contact part like a box and constructed as an overspring. The detent sleeve has a bottom wall, two side walls each having an overspring arm being cut out of the side wall, bent inward and resting on a respective one of the spring legs, a top wall being divided by a longitudinal slit, and a detent spring arm being cut out of one of the walls, extending in the longitudinal direction of the detent sleeve and being bent outward. The overspring arms are formed solely by dividing cuts extending substantially crosswise to a longitudinal direction of the detent sleeve.