Installing the Flatter
Loosen the strings enough so that they lose all their tension and pull them aside. (when installing the Flatter for the first time, you may want to detach the strings from the tuners entirely)
Place the edge of the Flatter on the side of the guitar or bass neck. (either side is fine)
Align the groove under the built in nut of the flatter above the nut of the guitar, and press on the other side of the Flatter until it snaps into place. The guitar's nut should fit into the groove.
In the event that the Flatter is slightly wider than your guitar neck, use the supplied foam stickers. Apply the stickers along one side of the flatter, and use this side first when installing. Then proceed as before.
After installing the Flatter, apply pressure to make sure it sits properly. Tighten the strings, tune your guitar and you are good to go.
To uninstall the flatter just loosen your strings and pull it gently off the guitar neck from either side.