assuming you know what it is
Less a problem with electronic boxes. But LEADS!!
I have a whole tangle* of leads that I might need for a camera or something. I haven't any idea what they are actually for or if I can dump them. Because the manufacturer of the unknown device used a non-standard, but unbadged lead. I have no idea what the were/are for until I find a device with a nonstandard connection and have to play match the plug then extract the lead from the tangle.
*It's one of those unexplored laws of nature. Place two or more cables in a dark, isolated space and leave them undisturbed for more than a week.and they will form an impenetrable tangle.