If a trailer didn't have a trailer jack, this means of transport would be pretty much useless – unless you are strong enough to lift it by hands or hitch (unhitch) a tow vehicle somehow else. Jacks can be manual and electric. With the help of an electric jack, you can hitch up substantially easier than with the manual unit, since a manual jack requires the application of physical force. Anyway, whatever the trailer jack you have, this part has to be completely workable and sufficiently reliable to prevent troubles during a journey under various conditions.
The cover has worked great. The reason for only 4 stars is that we took preventative measures when it arrived. Many reviews complained about it leaking. We turned it inside out and sealed all the seams. Once dry, we put a plastic bag on first and then this cover. Using both has made a water/weather proof cover to protect the electronics of our power lift. The plastic on its own is not strong enough, adding this cover made the difference.