Life Span TR800DT If space is a major concern, this standing treadmill desk is for you. At a mere 65 in length, the TR800-DT5 is the shortest treadmill desk on the market. The reduced footprint lets you easily fit the treadmill desk into areas of limited space while still supplying a large enough walking surface for varying stride lengths. Over a $900 new,m 3 years old in great condition.