Double:

* Low Headroom Track – See Double Track Low Headroom
* Shaft – Double torsion spring shaft that is utilized when more space is required for counterbalance spring lengths
* Strength Glass – A grade of glass that is typically ⅛” thick and lighter than most plate glasses
* Top Roller Fixture – A fixture located at the top section that features two top brackets that create a longer roller shaft
* Track Low Headroom – A second pair of horizontal tracks that reduce the height point of travel, allowing the door to be mounted in an area with minimal headroom