We offer a 4 or 6 bearing upgrade kit on most hubs. We install the bearings in our wheel shop prior to shipment. Just add this item to your cart along with the wheels at time of purchase. We recommend this upgrade for DT350 hubs as the more premium hubs come with more premium stainless bearings from factory!
Take a peek at Ard's blog if you want to learn more about Kogel and bearing tech in general, it is really excellent. We suggest you start here.