It's about 14mm wide and has 21 pins.
This is called a mezzanine connector. It interconnects directly two PCBs together. They are meant to provide "a mechanically secure, high density electrical interface between parallel printed circuit boards."
This specific connector is the 91930-21121LF, of the Conan/MezzSelect Series by Amphenol.
21 Position Connector Receptacle, Outer Shroud Contacts
From Jasen's comment and datasheet:
datasheet note 7 "the three slots may be located at either end"
the name of that connector should be "DIP pin connector" with 21p. check the length between the pin if the length between the pin (pitch) 1.27mm so your DIP connector is DIP female 1.27mm pitch 21p you can check either online or in Mouser.com
or i could be wrong but that's not like dip connector at all.. you could check the cable (male version) for making sure, it's usually have code either in female or male housing.