The 8100 ES is a folding treadmill and does not have a DMX adjustment as noted above. However, it is cheap and the motor belt will stretch after about 2 years, requiring the purchaser to replace ($22.50 plus $18 shipping). With treadmills, you get what you pay for, simple as that. I would not recommend this model or manufacturer to anyone.
Check and compare Treadmills here before you buy any.
Check my pricing, ongoing promotions, manufacturer, mark and model, etc then make a decision.