Side loading cardboard corrugated boxes 18″ x 6″ x 45″ 275#/ect-44 – 5 pack these cartons open along the ends for easy insertion of frames, mirrors and other flat products. designed with full overlap (fol) flaps for added protection manufactured from 275#/ect-44 kraft corrugated boxes are sold in bundle quantities of 5 and ship flat to save on storage space and shipping for help selecting the right box, click the brochure tab below.