A fiber optic cassette (10/110/210/310/410/610/810) comprising: a body defining a front and an opposite rear and an enclosed interior, the body further defining a top surface and a bottom surface which define major sides of the cassette body and extend between the front and the rear; a cable entry location defined in the body for a cable to enter the interior of the cassette (10/110/210/310/610/810), wherein a cable that enters at the cable entry location is coupled to the cassette body and fibers are extended into the cassette body and form terminations at first connectors; wherein the first connectors are connected to a rear side of adapters of an adapter block (40/120/320) located at the front of the cassette (10/110/210/310/610/810), each of the first connectors including a hub and ferrule and each of the adapters including a split sleeve, characterized in that the first connectors are connectors formed of only the ferrule terminating a fiber and the hub directly mounted to and contacting the ferrule, wherein the rear side of each adapter defines a structure for receiving the ferrule and the hub of one of the first connectors; wherein a front side of the adapters define termination locations for cables to be connected to the fibers connected at the rear side of the adapters, the termination locations configured to receive second fiber optic connectors (108/408) having a different format than the first connectors; wherein each second connector (108/408) is a traditional connector such as an SC or LC connector; and wherein the adapters along the front of the cassette body are arranged linearly and extend in a longitudinal direction parallel to the major surfaces defined by the top and the bottom of the cassette body. a body defining a front and an opposite rear and an enclosed interior, the body further defining a top surface and a bottom surface which define major sides of the cassette body and extend between the front and the rear; a cable entry location defined in the body for a cable to enter the interior of the cassette (10/110/210/310/610/810), wherein a cable that enters at the cable entry location is coupled to the cassette body and fibers are extended into the cassette body and form terminations at first connectors; wherein the first connectors are connected to a rear side of adapters of an adapter block (40/120/320) located at the front of the cassette (10/110/210/310/610/810), each of the first connectors including a hub and ferrule and each of the adapters including a split sleeve, characterized in that the first connectors are connectors formed of only the ferrule terminating a fiber and the hub directly mounted to and contacting the ferrule, wherein the rear side of each adapter defines a structure for receiving the ferrule and the hub of one of the first connectors; wherein a front side of the adapters define termination locations for cables to be connected to the fibers connected at the rear side of the adapters, the termination locations configured to receive second fiber optic connectors (108/408) having a different format than the first connectors; wherein each second connector (108/408) is a traditional connector such as an SC or LC connector; and wherein the adapters along the front of the cassette body are arranged linearly and extend in a longitudinal direction parallel to the major surfaces defined by the top and the bottom of the cassette body.