一般来说，伸缩门的长度建议定制在12m以下。如果超过12M，建议定制对开伸缩门，就好像我们普通的两扇门组成一道门一样。由于超长伸缩门在安装时需要一定的技术条件，在操作过程中，超长伸缩门容易偏斜或扭曲，损坏伸缩门的结构。另外加长版电动伸缩门的运输条件比较苛刻，运费会增加。如果是定制超长型电动伸缩门，我们建议定制带有轨道的，以保证伸缩门运行顺畅、笔直。下面我们通过一个案例来说明。
Generally speaking, it is recommended to customize the length of the expansion door to be less than 12m. If it exceeds 12M, it is recommended to customize the opposite retractable door, just like our ordinary two doors forming one door. Due to the need for certain technical conditions during the installation of ultra long expansion doors, they are prone to deviation or distortion during operation, which can damage the structure of the expansion door. In addition, the transportation conditions for the extended version of the electric telescopic door are quite strict, and the shipping cost will increase. If it is a customized ultra long electric telescopic door, we suggest customizing one with tracks to ensure smooth and straight operation of the telescopic door. Let's use a case study to illustrate.
曾经，我们遇到过这样一个客户，客户来找我们购买一条19米长的轨道。事实上，客户在几天前才安装了无轨伸缩门。在定制时，我们本来建议客户选择有轨伸缩门，因为19m伸缩门太长，但客户考虑到自己的情况选择了无轨伸缩门。
Once, we encountered a customer who came to us to purchase a 19 meter long track. In fact, the customer only installed the trackless telescopic door a few days ago. When customizing, we originally suggested that the customer choose a trackless expansion door because the 19m expansion door is too long, but the customer chose a trackless expansion door considering their own situation.
在使用过程中出现了很多问题。安装师傅因为客户的伸缩门跑偏，无法直线运行，多次上门服务。历时一个月，客户终于下定决心要换成有轨伸缩门。从安装伸缩门到更换有轨的过程中，虽然安装师傅上门维修是免费的，但是客户支付了两次安装费，增加了电动伸缩门的使用成本。
Many problems have arisen during use. The installation technician was unable to run in a straight line due to the customer's retractable door deviation, and has provided multiple on-site services. After a month, the customer finally made up their mind to replace it with a rail retractable door. During the process from installing the expansion door to replacing the track, although the installation technician's on-site maintenance is free, the customer paid two installation fees, which increased the cost of using the electric expansion door.