This is a 120-180 size heavy duty scale CNC 90° electric retract with scale struts installed including sequencer module. Measurements are shown in photo. Total length from mounting base to wheel center is approximatel 6-7 length. ACCEPTS 12.8 mm STRUT These retracts are ready for 11 mm struts but with the 5 mm adapter (included), you can quickly and easily change to a 5 mm strut if needed for smaller-sized planes (see photos). The voltage range is between 5 and 6 volts. Flexible, durable and dependable. How retracts should be.