With the advent of domestic containers in the mid-80s, CSX invested heavily in 48' boxes, first under the CSL name, then under CSX Intermodal. With the jump to the 53' standard, CSX chose to concentrate on steel corrugated boxes rather than ex-post or sheet-and-post designs. In addition to their own CSX Intermodal fleet, CSX is part of both the NACS and STAX domestic container pools.