A slide rail mechanism, comprising: a first rail; and a connection device, wherein the connecting device includes: a first component detachably connected to the first rail; a second component movable with respect to the first component; and an operating member configured for transversely displacing, and thereby adjusting, the second component with respect to a longitudinal length direction of the first rail, further comprising a second rail, with respect to which the first rail is longitudinally displaceable, further comprising a stopping structure disposed on one of the first rail and the second rail and a fitting detachably mounted on the other of the first rail and the second rail, wherein when the fitting is mounted on the other of the first rail and the second rail, and the first rail is retracted with respect to the second rail, the fitting is brought into abutment against the stopping structure in order for the first rail to be at one of a plurality of different longitudinal positions (P1, P2, P3) with respect to the second rail or at a same longitudinal position with respect to the second rail, the slide rail mechanism further comprising a base, wherein the base is connected to the other of the first rail and the second rail, and the fitting is detachably mounted at the base, wherein the fitting includes an adjustment device, the adjustment device includes an adjusting element, the adjusting element is adjustably mounted at the base, and when the first rail is retracted with respect to the second rail, the adjusting element is brought into abutment against the stopping structure, wherein the operating member is configured to transversely displace, and thereby adjust, the second component through eccentric adjustment, wherein the operating member includes a first portion, a second portion, and an operating portion; the first portion is a substantially circular protrusion; the second portion is connected to the first portion at a position other than a center of circle of the first portion; one of the first component and the second component includes a first structure; the other of the first component and the second component includes a second structure; the first portion of the operating member is inserted in the first structure; and the second portion of the operating member is inserted in the second structure; wherein the first structure is a first hole, and the second structure is a second hole, wherein the second hole is smaller than the first hole. a first rail; and a connection device, wherein the connecting device includes: a first component detachably connected to the first rail; a second component movable with respect to the first component; and an operating member configured for transversely displacing, and thereby adjusting, the second component with respect to a longitudinal length direction of the first rail, a first component detachably connected to the first rail; a second component movable with respect to the first component; and an operating member configured for transversely displacing, and thereby adjusting, the second component with respect to a longitudinal length direction of the first rail, further comprising a second rail, with respect to which the first rail is longitudinally displaceable, further comprising a stopping structure disposed on one of the first rail and the second rail and a fitting detachably mounted on the other of the first rail and the second rail, wherein when the fitting is mounted on the other of the first rail and the second rail, and the first rail is retracted with respect to the second rail, the fitting is brought into abutment against the stopping structure in order for the first rail to be at one of a plurality of different longitudinal positions (P1, P2, P3) with respect to the second rail or at a same longitudinal position with respect to the second rail, the slide rail mechanism further comprising a base, wherein the base is connected to the other of the first rail and the second rail, and the fitting is detachably mounted at the base, wherein the fitting includes an adjustment device, the adjustment device includes an adjusting element, the adjusting element is adjustably mounted at the base, and when the first rail is retracted with respect to the second rail, the adjusting element is brought into abutment against the stopping structure, wherein the operating member is configured to transversely displace, and thereby adjust, the second component through eccentric adjustment, wherein the operating member includes a first portion, a second portion, and an operating portion; the first portion is a substantially circular protrusion; the second portion is connected to the first portion at a position other than a center of circle of the first portion; one of the first component and the second component includes a first structure; the other of the first component and the second component includes a second structure; the first portion of the operating member is inserted in the first structure; and the second portion of the operating member is inserted in the second structure; wherein the first structure is a first hole, and the second structure is a second hole, wherein the second hole is smaller than the first hole.