Installation is easy. I saw it as Ok enough if I wanted to check how much marks remained, as the scale was written in% display. I installed it on a full tank drum and watched the scale, it stopped at the display of about 60% or more ... I checked several times as to how to install it, but after I checked the situation, the situation did not change and I contacted the manufacturer ... " It can not be displayed if the amount remains more than 60% "and" It is an item that can check the state where the number of days has come down. " There is no such description in the manual at all. Certainly it will not be a problem if we know "a situation that is going to go lost" but if we can display "full" tightly and "can not display" by that amount saves useless, can it be done more cheaply? I feel it. Childroid.