If you are installing a bearing race into a wheel hub, differential axel tube or other, you will need to first match the new bearing race to one of the preformed drive fittings of the tool. Once you've found the correct size fitting you will need to fit the drive fitting onto the handle of the bearing race driver handle and screw the drive fitting into place. Make sure that the angled mating face of the drive fitting is facing away from the handle and towards the mounting point. The bearing race will then slide into place on the drive fitting and can be placed into the opening of the wheel hub, differential axel tube or other mounting recess. All that is required now is to firmly grip the handle while allowing for safety clearance for hammer strikes to keep clear of your hand. Strike the handle of the Bearing Race Driver and you will be able to slowly drive the bearing race into place until it is seated in place at the bottom of the wheel hub, differential axel tube or whatever you're installing the bearing race into.
If you are planning to use the Bearing Race Driver to install a flat seal for something such as a timing cover or to install a cam plug to close the camshaft bore at the rear of an engine block, it would be advised to install the driver fitting backwards as compared to how you would install the bearing race driver fitting to install an actual bearing race. The concern is that while installing flat surface seals or cam plugs and freeze plugs, the face of the tool will become slightly scared from the hammer blows against the harder metals of the plugs of seals (the tool is made of a slightly softer aluminum). Installing a bearing race driver fitting with the larger flat side of the driver fitting will allow you to select a driver fitting that is either just larger or just smaller than the plug or seal and there will be no concern of the beveled edge of the bearing race side interfering with installation of the plug or seal. If you're installing a seal for something like a timing cover, you'll want the flat side of the bearing race driver fitting to be just smaller than the outer diameter of the seal you're installing. If you're installing a cam plug or freeze plug, you'll want the bearing race driver fitting to be a bit larger than the plug you're installing. Be aware some freeze plugs install into recessed bevels in the engine block or cylinder heads and would need a second round of hammering with a bearing race drive fitting that is just barely smaller than the outer rim of the freeze plug. (you can also use a large socket to try and push a plug just inside a beveled edge). Cam plugs are tricky to install because they have such a shallow rim but once you get the bearing race driver centered on the plug, you should be able to drive it in with only a few short solid blows from a hammer. Always keep in mind, if installing cam plugs or freeze plugs, you should clean and then coat the inner diameter of the cam plug or freeze plug port with a non-hardening sealant similar to Permatex No. 2B sealer.