Small box used to put batt. charger electronics MRB045 for DIY installation of Lion bateries in old appliances working on 12V from ordinary USB charger . Same box can be used for same electronic board with other voltages-depends on number of batteries inside.
Maybe it will be usefull to someone who likes to renew favorite electric tools :-)
*for better work, cooling openings are added in model
The author marked this model as their own original creation.