The SL is the only machine in the line that offers an upper 5.25" bay, and therefore the only model to offer two 5.25" bays, where the other models, including the SL/2 and the entire TL range, feature two upper 3.5" bays and one lower 5.25" bay. As a result, fitting a hard drive to an SL that already has the upper and lower 5.25" bays populated may require either the removal of one of the devices in those bays, or the installation of a hard disk card-style bracket which seats in one of the ISA slots.