It has no spacer, which can be lost; the different battery sizes instead be made with a feather perfect.
It is very good that the charging current can be adjusted in three steps. In order not to load the small batteries too quickly with too high amperage and do not "forever" to wait for the larger batteries until they are full.
I especially like that the voltage for each charging slot is displayed separately; I'm too lazy to try my voltmeter each time. And without voltage control I would Li-ion battery - not load - because of your enormous risk potential.
