The guitarrón mexicano (the  Spanish name of a "big Mexican guitar", the suffix "-ón" being a Spanish augmentative) or Mexican guitarron is a very large, deep-bodied Mexican six-string acoustic bass played traditionally in mariachi groups. Although similar to the guitar, it is not a derivative of that instrument, but was independently developed from the sixteenth-century Spanish bajo de uña ("fingernail[-plucked] bass"). Because its great size gives it volume, it does not require electric amplification for performances in small venues. The guitarrón is fretless with heavy gauge strings, most commonly nylon for the high three and wound metal for the low three. The guitarrón is usually played by doubling notes at the octave, a practice facilitated by the standard guitarrón tuning A1 D2 G2 C3 E3 A3. Sometimes the high A is lowered an octave, putting it just one octave above the low A.