These smooth (round) belts have a Durometer hardness of A70 and can withstand temperatures from -35 to 250 degrees F. Their elastic nature allows them to apply tension on the pulleys when stretched and the rubber construction creates excellent grip characteristics between the pulley and belt. Smooth belts can be used in a variety of applications including follow focus systems, linear drives, 90 degree drives, XY tables, robot tracks, battery hold-downs, etc.
[Actobotics](https://www.sparkfun.com/pages/Actobotics) is a robotics building system based around extruded aluminum channels, gears, precision shafts, and ball bearings. Thanks to the two standardized hole patterns, nearly all Actobotics components can be intuitively connected together. The wide range of components makes building complex electromechanical prototypes or finished projects a reality.
**Note:** These belts have a stretch factor of 12-26%. A low stretch factor will apply a small amount of side-load to the axles and create less friction while a higher selected stretch factor will apply slightly more side-load to the axles and have more resistance to belt deflection.
* [Product Page](http://www.servocity.com/html/smooth_belts.html) (636136)