Covering long distances in a wheel chair is hard on the arms of its user, but it may not happen often enough to justify the cost of a new electric wheelchair. At the Tokyo Motor Show last week a prototype WHILL, an electric drivetrain clamp for manual wheelchairs was demonstrated. The device is U-shaped and has two hubs that attach to the outside center of the wheels and a control center that curves over the user’s lap. The user drives it by leaning in the direction he wants to turn.

Each hub has a 24-volt motor powered by a lithium-ion battery pack. After a two-hour charge, the drivetrain has a range of 19 miles and a speed as high as 12.5 mph. The product isn’t ready for the market just yet, but the Japan-based company is looking for wheelchair users to test the device.