A multi-drop closure system for containing and managing a bundle of optical fibers, the multi-drop closure system comprising: an enclosure including a cover and a base that collectively define an enclosure chamber, the base including a floor, opposed end walls, and opposed sidewalls, the cover being at a top of the enclosure chamber and the floor being at a bottom of the enclosure chamber, the enclosure chamber including a slack basket chamber to hold the bundle of optical fibers; and a slack basket system including a plurality of retainer tab assemblies mounted in the enclosure, each retainer tab assembly including a respective tab base that is mounted in a recess of a respective one of the opposed sidewalls of the enclosure, and a respective tab member movable between: an open position, wherein each tab member is positioned to provide more open access to the slack basket chamber and thereby enable the bundle of optical fibers to be more easily inserted into, removed from, and/or manipulated in the slack basket chamber; and a retaining position, wherein each tab member overlaps the slack basket chamber to retain the bundle of optical fibers in the slack basket chamber; wherein each tab member partitions the enclosure chamber into each of the slack basket chamber below each tab member and a tray chamber above each tab member; a plurality of trays pivotally mounted in the tray chamber, the plurality of trays overlying the slack basket chamber, the plurality of trays being configured to hold optical fiber splices; wherein the plurality of trays is supported by at least one tab member; and wherein the retainer tab assemblies each include a strap slot therein, and the multi-drop closure system further includes a strap extending over the plurality of trays and through the strap slot to secure the plurality of trays to each retainer tab assembly. an enclosure including a cover and a base that collectively define an enclosure chamber, the base including a floor, opposed end walls, and opposed sidewalls, the cover being at a top of the enclosure chamber and the floor being at a bottom of the enclosure chamber, the enclosure chamber including a slack basket chamber to hold the bundle of optical fibers; and a slack basket system including a plurality of retainer tab assemblies mounted in the enclosure, each retainer tab assembly including a respective tab base that is mounted in a recess of a respective one of the opposed sidewalls of the enclosure, and a respective tab member movable between: an open position, wherein each tab member is positioned to provide more open access to the slack basket chamber and thereby enable the bundle of optical fibers to be more easily inserted into, removed from, and/or manipulated in the slack basket chamber; and a retaining position, wherein each tab member overlaps the slack basket chamber to retain the bundle of optical fibers in the slack basket chamber; an open position, wherein each tab member is positioned to provide more open access to the slack basket chamber and thereby enable the bundle of optical fibers to be more easily inserted into, removed from, and/or manipulated in the slack basket chamber; and a retaining position, wherein each tab member overlaps the slack basket chamber to retain the bundle of optical fibers in the slack basket chamber;