The Graph Tech 5-string Ratio 2+3 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-5230 is a right-handed set of Ratio calibrated machine heads for bass guitars that use 2 x 3 configuration.