The Spirit XT685 is a great choice for the home or commercial environment. The console is equipped with a unique muscle activation profile system. It’s important to understand which muscle groups are gaining the most benefit during your work-out. On our treadmills, you will be using your glutes (bottom), hamstring (back of your thigh), quad (thigh), calf, & pecs & arm muscles. The LED’s lights will activate in two degrees of engagement: Amber represents medium involvement, & Red, full or heavy involvement. Use this quick reference to challenge yourself during your work-out. The XT685 has a oversized 22” X 60” running belt surface, commercial flatbed deck with superior cushioning & duraweave running belt. 3.0 CHP quiet drive motor enabling a maximum speed of 12mph. Whisper quiet elevation motor with incline options of 0-15% for superb workouts. Integrated cooling fan & 2 speakers for MP3/ Ipod jack (connector included) Handle based speed/elevation controls with disable switch. Direct select program/speed & incline buttons for easy console changes. Heart Rate Control programming (chest strap included for more accurate HR reading)