The 2 wheels’ height-adjustable roller is a heavy duty roller with the same size as heavy duty lift-sliding door rollers. It gives the possibility to make passive leaf a sliding door beside the active lift-sliding door leaf.
The patent roller has two unique features. The cover of the roller can protect the wheels during installation and transportation, which will be removed only when mounting at the site. The brushes at each end of the roller will clean ground rails, ensuring a long lifetime for the roller.