Pinarello is one of those manufacturers that use a proprietary integrated headset design in their high-end bike frames. We've never had any issues with them. In fact, we have trouble recalling anyone ever calling with a need for replacement bearings.
Nevertheless, it doesn't matter how good the factory bearings are, they'll eventually need service and potentially replacement. So if you've got a million miles on your Pinarello and have noticed the headset getting a bit notchy, then these are what you'll need. We have them in three versions -- FP 1.25", FPX 1.25" and Prince 1.125".
The Prince 1.125" works as the upper bearing for all models in addition to being the lower bearing used in the Paris Carbon, F4:13, FP6, and Prince SL. The FP is the lower bearing for the 2006 magnesium Dogma FP. The FPX is the lower bearing for the Dogma Carbon, Prince Carbon, Dogma FPX, FP3, and FP7.
Please Note: You'll want to have a qualified mechanic (you or otherwise) do the replacement as the bearings have to be pressed out/in with the appropriate tools.