Available Align T-REX 550X Dominator Kits - Super Combo and Combo.

The difference between the T-REX 550X Super Combo RH55E18XW and T-REX 550X Combo RH55E19XW Kits is servos.

The 550X Super Combo includes DS820M Digital Cyclic Servos x 3 and DS825M Digital Tail Servo x 1 (servos have a full metal case). The 550X Combo includes DS820 Digital Cyclic Servos x 3 and DS825 Digital Tail Servo x 1 (top and bottom of servos case is not metal). Both have metal gears.