R-116 – designed for 700 class electric or nitro helicopters with low tail ratios (Synergy E7) – Buy Now

R-106 – designed for 600 – 700 class helicopters (Synergy E5, N5c, E7SE, N7) – Buy Now

R-96 – designed for 550 – 600 class electric or nitro helicopters (Synergy E5, N5c) – Buy Now

R-80.6 – designed for 500 class electric or nitro helicopters (Goblin 500, Gaui Nx4,) – Buy Now