I have a lot of these lying around. I make them with different connectors depending og what battery I am going to measure. So I have one in my FPV-drone box, one in the box with the RC cars, one besides the battery charger etc.

It is made for this digital voltmeter: http://www.banggood.com/0_28-Inch-2_5V-30V-Mini-Digital-Voltmeter-p-974258.html

I add a bit of UHU patafix glue pads before I close it. That way it will sit tight but I can still open it again and trim the voltage level etc.