Slide rail assembly

A slide rail assembly, comprising:

• a first rail comprising a first structure, a second structure and a first severing feature;
• a second rail movable relative to the first rail;
• a third rail movable relative to the second rail, the third rail having a synchronizing feature;
• an operating member arranged to the first rail, the operating member comprising a first blocking portion, the second rail having a second blocking portion;
• a positioning device arranged to the second rail, the positioning device comprising an elastic member and a positioning member, the positioning member being located at an initial position in response to an elastic force generated by the elastic member;
• and
• a synchronizing member arranged to the second rail;
• wherein the second rail and the third rail are movable relative to the first rail synchronously from a first position to a second position in a first direction by means of abutting between the synchronizing feature and the synchronizing member until the first severing feature of the first rail severs a synchronous relationship between the second rail and the third rail;
• wherein when the second rail and the third rail are at the second position, the positioning member is moved from the initial position to an engaging position through the elastic force released by the elastic member and abuts against the first structure of the first rail to prevent the second rail from being moved relative to the first rail in a second direction, and when the first blocking portion of the operating member is located at a blocking position, the first blocking portion and the second blocking portion are able to obstruct each other to prevent the second rail from being moved in the first direction;
• wherein the operating member is operable to drive the first blocking portion to leave the blocking position and no longer obstruct the second blocking portion such that the second rail is movable relative to the first rail to a third position in the first direction, the positioning member is moved from the engaging position to a disengaging position by guidance of the second structure of the first rail and no longer abuts against the first structure of the first rail.