A fiber optic cassette mounting system, comprising: a multi-gang fiber optic cassette; and a fiber optic cassette tray comprising rail guides configured to engage with respective rails of the multi-gang fiber optic cassette, wherein a rail guide, of the rail guides, comprises an elongated portion of a surface of the fiber optic cassette tray that is raised from the surface to form ledges on a left side and a right side of the elongated portion, wherein the rail guides are configured to hold a single-gang fiber optic cassette and the multi-gang fiber optic cassette simultaneously on the fiber optic cassette tray; and wherein the multi-gang fiber optic cassette comprises: a housing comprising at least a first gang and a second gang configured to house optical fibers; a left rail disposed on a left side of the multi-gang fiber optic cassette; a right rail disposed on a right side of the multi-gang fiber optic cassette; a clearance area disposed between the first gang and the second gang; and a latching mechanism disposed within the housing and comprising a spring and a release mechanism that interacts with the spring, wherein the latching mechanism is disposed above the clearance area; wherein the left rail and the right rail are configured to engage with respective rail guides (108C, 108E) of the fiber optic cassette tray to facilitate mounting the multi-gang fiber optic cassette on the fiber optic cassette tray, wherein adjacent rail guides (108C, 108D; 108D, 108E) of the fiber optic cassette tray define a cassette bay configured to receive a single-gang fiber optic cassette, the multi-gang fiber optic cassette is configured to span at least two cassette bays of the fiber optic cassette tray when mounted on the fiber optic cassette tray; and wherein the clearance area comprises a groove on a lower surface of the housing configured to allow a rail guide of the fiber optic cassette tray to pass under the multi-gang fiber optic cassette. a multi-gang fiber optic cassette; and a fiber optic cassette tray comprising rail guides configured to engage with respective rails of the multi-gang fiber optic cassette, wherein a rail guide, of the rail guides, comprises an elongated portion of a surface of the fiber optic cassette tray that is raised from the surface to form ledges on a left side and a right side of the elongated portion, wherein the rail guides are configured to hold a single-gang fiber optic cassette and the multi-gang fiber optic cassette simultaneously on the fiber optic cassette tray; and wherein the multi-gang fiber optic cassette comprises: a housing comprising at least a first gang and a second gang configured to house optical fibers; a left rail disposed on a left side of the multi-gang fiber optic cassette; a right rail disposed on a right side of the multi-gang fiber optic cassette; a clearance area disposed between the first gang and the second gang; and a latching mechanism disposed within the housing and comprising a spring and a release mechanism that interacts with the spring, wherein the latching mechanism is disposed above the clearance area; wherein the left rail and the right rail are configured to engage with respective rail guides (108C, 108E) of the fiber optic cassette tray to facilitate mounting the multi-gang fiber optic cassette on the fiber optic cassette tray, wherein adjacent rail guides (108C, 108D; 108D, 108E) of the fiber optic cassette tray define a cassette bay configured to receive a single-gang fiber optic cassette, the multi-gang fiber optic cassette is configured to span at least two cassette bays of the fiber optic cassette tray when mounted on the fiber optic cassette tray; and wherein the clearance area comprises a groove on a lower surface of the housing configured to allow a rail guide of the fiber optic cassette tray to pass under the multi-gang fiber optic cassette. a housing comprising at least a first gang and a second gang configured to house optical fibers; a left rail disposed on a left side of the multi-gang fiber optic cassette; a right rail disposed on a right side of the multi-gang fiber optic cassette; a clearance area disposed between the first gang and the second gang; and a latching mechanism disposed within the housing and comprising a spring and a release mechanism that interacts with the spring, wherein the latching mechanism is disposed above the clearance area; wherein the left rail and the right rail are configured to engage with respective rail guides (108C, 108E) of the fiber optic cassette tray to facilitate mounting the multi-gang fiber optic cassette on the fiber optic cassette tray, wherein adjacent rail guides (108C, 108D; 108D, 108E) of the fiber optic cassette tray define a cassette bay configured to receive a single-gang fiber optic cassette, the multi-gang fiber optic cassette is configured to span at least two cassette bays of the fiber optic cassette tray when mounted on the fiber optic cassette tray; and wherein the clearance area comprises a groove on a lower surface of the housing configured to allow a rail guide of the fiber optic cassette tray to pass under the multi-gang fiber optic cassette.