If it's minimal maintenance you're after, these quality PVC belts with impregnated lubrication require less attention to make things run smoothly.
This Sportsmith treadmill running belt fits Horizon T401 treadmills, Serial# TM603*

User facing material: PVC
User facing surface: Black Diamond
Impregnated Lubrication
Finger-spliced seam
1 ply

*Some machines with the same name use different parts. This is why you should always match your model# or serial#.