[Heavy-Duty Structure]: Box rail barn door hardware kit is made of super quality heavy steel with black powder coating on the surface to prolong the service life; Smooth and Quiet when used.box rail exterior barn door hardware is protected by high quality materials for optimal corrosion resistant even in outdoor use. [Reminds]: 6.6FT/79.2" box rail kit is suitable for 39.6"~40" wide door panels; Fit door thickness: 1" ~ 1-13/16"(25mm~46mm); Bearing capacity: 330LBS; at least 4" clearance needed from top of door and ceiling. [Package Includes]: (3) Splicing Box Guide Rail; (2) Track Connector; (6) Wall Anchors; (2) Roller; (2) Hanger; (2) Door Stop; (2) End Cap; (1) Floor Guide; All parts required for box rail barn door hardware kit installation. NO DOOR PANEL. [Installation]: We povided step-by-step Graphic&Text installation manual is attached to the box rail hardware package; Install video; Professional online installation guidance. [24 Hours Support] BONIKLUBA has a professional customer support team. Please let us know, if you encounter any questions or troubles, we will actively answer them for you.