[quote=@TheWindel]
Are UNITs customizable or do they always have to be palm boxes.
[/quote]

Entirely customizable. They're usually the size of one's palm as they're non-combatants, but I'm not going to limit reasonable change. They're only a black box as in the black box of a plane. In the event of emergency, they can be used to figure out what happened. The design of them can vary significantly, depending on age, manufacturer, after-market upgrades, or just someone shoving every single sticker they find onto one.