I know there are two companies doing this in Jinan, Yi Jie Jinan Chain Store and Mars. I consulted these two companies when I installed the navigation. The principle is basically the same, and the quotation is similar. I'm near Jinan Station in Yi Jie, and I'm in Qilu Pharmaceutical. My neighbor, Yun Tong Auto Parts City, and I went to Jinan Station in Yi Jie, both of which did quite well. The master is very skilled at first glance, and there is a warranty, which is close and good after-sales.