think that the driver is in trip when the tyre breaks, he is obliged to replace one! changing tyre is a very inconvenient thing, especially by open country highway, in the hot, chilliness weather or the moment raining or snowing. using the manual jack to change tyre is wasting time and energy. and, some ladies and gentlemen are not enough strength to jack up the automobile by shaking the manual jack. but using the electric car jack to change tyre is easy, quick and convenient! only plug the dc plug into the vehicle¡¯s cigarette lighter receptacle, set the electric jack on the right position which appointed for jack, then press the button. the electric car jack can easily lift the automobile by itself. it is relaxing to operate.