Halves

From YoYo Wiki

The halves of a yo-yo are the two sections that screw together using the axle, and are usually made of plastic, wood, or metal. With yo-yos that are unscrew you can take the two halves apart to untangle knots or change pads or bearings.

How your halves are set have a huge effect on how your yo-yo will look, feel and play; and as the sport advances new innovations are being made that enhance the halves both performance wise and in terms of aesthetics.

One of the simplest ways that you can improve the halves is to add rim weight, thus increasing kinetic energy and lengthening the moment of inertia. One of the simplest ways to achieve this is to remove the pogs (if applicable) and put in washers or rubber o-rings (conversely, adding center weight will allow better loops and gyro flops).