Here is another compact treadmill that combines with your smartphone to give you a good workout in small rooms and offices. The Egofit Walker M1 Under Desk Treadmill has 5% incline and a speed range of 1 to 5 km/h. It is powered by a HP motor.
This treadmill has a running area of 87 x 42cm. It has max weight capacity of 242.5lbs. It weighs only 48.5 lbs, so you can easily take it around. You can find out more about it here.