Recommended for slow powered conveyor and gravity conveyor applications. Not recommended for high speeds. Overlapping parts of the bearing housing create a labyrinth shield that helps prevent debris from getting inside the bearing, without creating rotational drag. This is most effective against large debris in small amounts. Large amounts of debris can get lodged in the labyrinth, especially when moisture is present. Not recommended for dusty environments. The rear shield can direct grease into the bearing allowing it to be regreased through the axle. Bearings that are regularly regreased can withstand very high levels of debris without damage.