This is sacrilege!
Stability - The more stable the treadmill, the more comfortable you feel using it. You don't want it to shake or wobble when you pick up the pace. You get what you pay for in this area. Higher end treadmills generally feel more stable than those under $1000. https://www.treadmillfit.net/merax-jk1604-easy-assembly-folding-electric-treadmill/