Does anyone know? They do not seem to be a type of JST connector - the slot on the bottom is off-center. I've done basic Google searches and even a Google Image search and can't figure it out. They seem to be 2.5mm pitch.
I managed to find a closeup of a similar board with the connector plugged in:
Here's closeups of the connectors. Notice the slot on the bottom is off-center, so it doesn't match any of the JST connectors, because they're symmetrical.
That does seem to be the part, here's the matching plug:
And I found that regular servo connectors work too.
Since these seem to be $3.00 each from Digikey or Mouser, plus shipping, that gets me to $20.00 for four pigtail connectors. So I'll likely just use servo connectors plus hot glue.