They're called "closed loop." A simple Google search showed me a plethora of sizes.
Misumi has a configurable length anywhere from 66 to 994mm. They call it 2GT.
Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus