When looking at battery charging balancing cables, they are said to have a "JST" connector.
This is of course not very specific -- just like "Molex" makes lots of different connectors, "JST" also makes lots of different connectors.
So, for the rectangular balancing adapters, which JST connector series are those actually using?
Looking at digi-key, the closest I can find is the PH series:
http://www.jst-mfg.com/product/pdf/eng/ePH.pdf