The Graph Tech 5-string Ratio 3+2 Bass Y-Style button tuning machine heads incorporate different string gauges into the tuning equation. Graph Tech balanced the gear ratios to each string, simplifying the tuning process. With Ratio, a half turn is a semi-tone. Every string reacts the same to any tuning adjustments, delivering predictable, precise tuning on every string. The Graph Tech PRB-5320 is a right-handed set of Ratio calibrated machine heads for bass guitars that use 3 x 2configuration.