The CBC SPEC bearing was developed to provide the best play and performance found in modern performance yo-yos. Made of stainless steel, these bearings will hold up to anything you can throw at it.
Taking it a step further, the CBC SPEC X is the newest SPEC and features a tighter configuration with smaller balls to reduce friction even more and increase spin time.
This bearing is called the HALF-SPEC because it is half the width of the normal size C bearing. This allows it to be used in responsive (tug-return) yoyos as the yoyo halves are closer together, bringing the yoyo string closer to the response system (ie. response pads).
Some normal-width Size C yoyos can have one of these HALF-SPEC bearings installed to convert an unresponsive yoyo to a responsive one, however, this does not work on all models, and may require a shorter axle.