sparkfun ESP8266 - Page 12

Or you can mix and match headers to best fit your needs. Right-angle male headers may help
to interface between the FTDI and the Thing. Straight male headers are a good choice for
low-profile connections. Straight female headers may help with connecting to I2C sensors.
And, of course, wire can be soldered to any of the pins that have a long way to connect to
something.