High-end aluminum alloy doors and windows are not only reflected in the price, but also in the design, workmanship and service quality of the door and window products. The performance of doors and windows is different due to the different scope of use, but the following aspects are usually considered: Strength: This is mainly reflected in the selection of materials for doors and windows, whether they can withstand ultra-high pressure; Air tightness: It is mainly reflected in the structure of doors and windows, whether the inner leaf and outer frame structure of doors and windows are tight, and whether the doors and windows are tight. Mute: The mute level of the entire series of doors and windows is not less than 30db, and high-end products can achieve a mute level of 45db; Energy saving: The highest K value of the whole series of doors and windows is ≤2.0, and the K value of the passive house product series is ≤0.73, and it has obtained the German (PHI) and EU Passive House certification; Watertight/airtight: multi-chamber design, enhanced sealing; three rubber strips seal to form three ultimate protections, EPDM rubber strips, instead of hard PVB rubber strips, fully ensure the airtightness of doors and windows. Beautiful: lifelike surface treatment method, HFL right-angle processing method; Durability: 36000Hr durability test, 6000Hr surface texture durability test; Safety: The most suitable place to relax is the place you think is safe. Multi-lock point setting, mushroom head lock point, 5mm inlaid hardware, etc., fully ensure the safety of doors and windows. bi folding doors uk sizes cost to install bi folding patio doors can french patio doors have screens aluminum sliding door lock price