Recommended for mid-sized loads at slower speeds. A felt seal holds out small amounts of large particle debris. A hole through the inner race allows the bearing to be regreased through the axle. Bearings that are regularly regreased can withstand very high levels of debris without damage. Grease lubricates the bearing so it is recommended for lineshaft applications as well as gravity applications. The grease creates rotational drag so it is not recommended for extremely light weight gravity applications. Not recommended for high speeds or CDLR.