The slack key guitar comes from Hawaii. It's an old tradition but since the island is so isolated, it remained quite unknown outside of Hawaii. The Hawaiian word for it is Ki ho'alu which means loosen the key when translated. This instrument is intended for finger picking style of playing. The keys and strings are slacked in order for the player to create more beautiful and diverse tones.The tuning's always in major tonality or it can contain a full major chord usually somewhere between the 6th and 7th note.There's a whole festival dedicated to the slack key guitar.