A fiber optic apparatus, comprising: a chassis defining a front end , a rear section , a first end , and a second end opposite the first end ; and at least one guide system disposed within the chassis and configured to receive fiber optic modules from the rear section of the chassis and guide the fiber optic modules toward the front end of the chassis ; wherein: the at least one guide system is comprised of module rail guides with channels disposed within the module rail guides configured to receive the fiber optic modules ; the fiber optic apparatus further comprises a plurality of fiber optic equipment trays arranged in a column format wherein the module rail guides are disposed on the fiber optic equipment trays to receive the fiber optic modules; wherein the channels of the module rail guides are open at their rear end so that the fiber optic modules can be installed from the rear of the chassis ; wherein the fiber optic apparatus includes a module stop or locking feature disposed adjacent the front end of the chassis, which stop or locking feature is configured to engage with a corresponding stop or locking feature at the modules to prevent the fiber optic modules from extending from the front end of the chassis when the fiber optic equipment trays are not extended unless the engagement between the stop or locking features is released, so that the fiber optic modules can also be extended and removed from the front end of the chassis ; the fiber optic apparatus being characterised in that the guide system also comprises tray rail guides receiving the fiber optic equipment trays from the front of the chassis and being provided with a rear stop wherein each of the plurality of fiber optic equipment trays is independently translatable within the chassis. a chassis defining a front end , a rear section , a first end , and a second end opposite the first end ; and at least one guide system disposed within the chassis and configured to receive fiber optic modules from the rear section of the chassis and guide the fiber optic modules toward the front end of the chassis ; wherein: the at least one guide system is comprised of module rail guides with channels disposed within the module rail guides configured to receive the fiber optic modules ; the fiber optic apparatus further comprises a plurality of fiber optic equipment trays arranged in a column format wherein the module rail guides are disposed on the fiber optic equipment trays to receive the fiber optic modules; the at least one guide system is comprised of module rail guides with channels disposed within the module rail guides configured to receive the fiber optic modules ; the fiber optic apparatus further comprises a plurality of fiber optic equipment trays arranged in a column format wherein the module rail guides are disposed on the fiber optic equipment trays to receive the fiber optic modules; wherein the channels of the module rail guides are open at their rear end so that the fiber optic modules can be installed from the rear of the chassis ; wherein the fiber optic apparatus includes a module stop or locking feature disposed adjacent the front end of the chassis, which stop or locking feature is configured to engage with a corresponding stop or locking feature at the modules to prevent the fiber optic modules from extending from the front end of the chassis when the fiber optic equipment trays are not extended unless the engagement between the stop or locking features is released, so that the fiber optic modules can also be extended and removed from the front end of the chassis ; the fiber optic apparatus being characterised in that the guide system also comprises tray rail guides receiving the fiber optic equipment trays from the front of the chassis and being provided with a rear stop wherein each of the plurality of fiber optic equipment trays is independently translatable within the chassis. <EOS>