,

YF-4SQ / YF-4AQ

YF-4SQ(Steel tube) YF-4AQ(Alloy tube)
,

YF-4S / YF-4A

YF-4S(Steel tube) YF-4A(Alloy tube)
,

YF-3SQ / YF-3AQ

YF-3SQ(Steel tube) YF-3AQ(Alloy tube)
,

YF-3S / YF-3A

YF-3S(Steel tube) YF-3A(Alloy tube)