The usual way to determine actual bearing size and spec is to take them out and measure. Then there's no chance the component wasn't changed from what was published is some spec book. I suspect much of the spec you read in the "book" is about the cups and their interfacing with spacers and such and not the actual bearings. There's a very good possibility that the same bearing cartridge is uses through a series of headset models. Andy


PS- IIRC Felt changed hands recently. If so don't be surprised if there are hick ups in communication or dealings with the current version of Felt when an old model is the subject.