Xnova 2207 Freestyle smooth line Combo 4 Pcs. - Choose KVFor superb smooth flight video recordings. High performance and finest CNC quality. Low cogging torque and smooth running. Precisely balanced and fully tested The XNova FS Line engines are 2207, their difference with the FH Line is that they are much more smooth at the expense of their power. the FS Line are made in particular for the movements ample and quite soft, a fluid behavior in flight, hence its SMOOTH name The FH Line are they much more