How Do I “Stack” Brook UFB and Brook Retro Board

The FAQ at jasenscustoms.com provides some information regarding how to stack a non-“stack-ready” Brook UFB (i.e., without the pins on the bottom of the board) on top of a Brook Retro Board.

https://jasenscustoms.zendesk.com/hc/en-us/articles/360010090372-Can-I-use-my-existing-UFB-in-my-Panzer-with-the-Brook-Retro-Board-

The directions explain that a 4-pin header must be soldered onto the bottom of the UFB (it actually says Solder to the Retro Board but I’m fairly certain that’s a mistake) so that it can be plugged into the Retro Board. From pictures I found online, the pin header appears to be a dual insulator type.

Question: Can anyone identify the precise type of header he is talking about? Any educated guesses are welcome too. I would greatly appreciate any information, whether it is a link to a product page or the dimensions of the pin header. I have been looking for this information for a long time to no avail.

Thanks everyone!