1 1/2 end, 1 1/2 side construction. Medium duty for use with or without shelving. Quick set-up assembly. Deep locking lift-off lid stays in place for secure file storage. Rolled edges add strength and prevent paper cuts. Stock up and save! Box Type: Quick Set-Up; Material(s): 1 Ply Bottom; 1 Ply End; 1 Ply Side; Strength: Medium-Duty; File Size Format: Letter/Legal.