My bass guitar amp does not have a DI out, so this has had a permanent place in my gig bag for years. Even well equipped venues sometimes run out of DI boxes and this box has often saved the day.
I also use it as an additional XLR tap off from my bass to my in ear monitor mixer, to allow me to mix my bass level with the rest of the band without having to signal to the monitor mix engineer,
In a pinch I've used it for studio recording too.
Changing the battery is a bit tricky, but no big deal as the battery is only a backup - the box is usually driven by phantom power from the mixing desk.
Would definitely buy again if it went missing.