Similar to the design of sliding doors found in automobiles, the design of Lift-slide doors is based on the separation of sliding action and sealing/locking action: Starting from closing position, with the weather-stripping engaged in compression, a 180 degree turn of the door handle unlocks the door and lifts it up by about ½", thus allowing it to slide easily without rubbing against any weather-stripping. As a result, the weather-stripping will not wear out pre-maturely and the doors require no effort to slide. Due to their ease of operation and because of their multi-point locking hardware, lift-slide doors can be built to the size of entire walls: they are the ideal choice when an entire wall is desired to open up to the outdoors ("indoor-outdoor living") such as sun-rooms or rooms with a view. Key Features: Easy and effortless to operate. For up to 40' wide openings. Low threshold (wheelchair accessible). High security and energy efficiency, due to multi-point locking hardware ( SIGENIA/HTL). Easy installation due to "click-in" door hardware. Solid construction, due to 2 3/8" thick sash and frame, with double mortise-and-tenon joinery. High energy efficiency due to compression weather-seal on all 4 sides. Full range of glazing options (standard glass: ¾ overall-DS clear tempered). Custom sizes and custom designs, including multi-panel arrangement and large sizes. Made from laminated solid vertical grain Douglas-Fir or a wood of your choice.