Slide rail system and connecting device used for slide rail assembly

A slide rail system comprising:

• a slide rail assembly comprising:
• a first rail having a longitudinally extending main body;
• and
• a second rail longitudinally slidable relative to the first rail, the second rail having a longitudinally extending main body, a front portion, and a mounting hole adjacent to the front portion;
• and
• a front connecting device comprising:
• a first unit having at least one transverse guiding portion;
• a second unit having at least one transverse guiding portion located at the transverse guiding portion of the first unit;
• an engaging element connected to the second unit, the engaging element having an engaging portion at least partially located in the mounting hole of the second rail;
• and
• an adjusting element having an adjusting portion and a screw rod, the screw rod being connected to the first unit and the second unit;
• wherein the second unit is displaceable relative to the second rail in response to rotation of the adjusting portion of the adjusting element, thereby enabling displacement of the engaging portion of the engaging element relative to the mounting hole of the second rail.