While inheriting the smooth feeling and good fuel efficiency of the previous model O.S.SPEED R21GT, the power feeling in the medium and low-speed ranges has been improved by revising the counterbalance of the crankshaft. In addition, the newly designed inner head improves idling performance, and an inner head O-ring is used to reduce vibration and improve dust resistance. The outer head has been made lighter and has evolved into the O.S.SPEED R21GT II with attention to detail. We also have a combo set with TB01 (EFRA2042) tuned silencer and MB01-70 manifold.