The Adafruit Data Logger shield comes tested assembled with all components and SD socket already on it, but you'll still need need to put headers on so you can plug it into an Arduino
We don't pre-assemble the headers on because there's two options! You can either use plain 0.1" male headers (included with the shield) or Arduino Shield Stacking headers. Both options additionally require a 2x3 female header soldered on.
Most people will be happy with assembling he shield with male headers. The nice thing about using these is they don't add anything to the height of the project, and they make a nice solid connection. However, you won't be able to stack another shield on top. Trade offs!
Cut the headers to length:
Line the header strip up with the holes on the edge of the shield and cut 4 sections of header strip to fit.
Position the headers:
Insert the header sections - long pins down - into the female headers on your Arduino/Metro. Additionally insert the 2x3 female header into the corresponding pins on the opposite side as the USB.
Solder each pin to assure good electrical contact. For tips on soldering, refer to the Adafruit Guide to Excellent Soldering.
Stacking headers give your data logger shield extra flexibility. You can combine it with other shields such as the RGB/LCD Display shield to make a compact logging instrument complete with a user interface. You can also stack it with one or more Proto-Shields to add even more prototyping space for interfacing to sensors.
Stacking headers are installed from the top of the board instead of the bottom, so the procedure is a little different than for installing simple male headers.
Insert the headers from the top of the shield, then flip the shield over and place it on a flat surface. Straighten the headers so that they are vertical.
Solder each pin for a solid electrical connection.
Tip: Solder one pin from each header section. If any of them are crooked, simply re-heat the one solder joint and straighten it by hand. Once all headers are straight, continue soldering the rest of the pins.