Two types: This floor width adjustable track is suitable for pre slotted doors and slotless doors.We suggest using higher wall brackets to save bottom door space.Improvement: The forearm interferes with the hole position of the rear arm, and the structure of the rear arm is redesigned to improve the interference problem.Design: Two hole holder for smoother operation.Make sure the door does not need to be grooved and will not damage your beautiful floor.【Quality】Ensure successful installation of stainless steel sliding barn doors.Before purchasing, please refer to the measurement values in the photo, check the gap between the door and the wall, the bottom gap of the door, and continue to slide it into place.After-sales satisfaction: If there are any missing or damaged parts, please contact us via Amazon email.