Linear bearings are used for linear motion. They can be used to build economic and simple linear guiding systems for a wide variety of applications such as CNC.
Precision Linear Bearing 12.00MM
Outside Dimensions: 21.00mm x 30.00mm
This linear ball bearing is slide along an 8mm linear shaft. These are very slim, and good for when you want to attach a motion carriage onto a railing without adding a lot of weight. These are very basic bearings, they are meant for a stepper-motion controlled.