With simple, lightweight designs, these bearings are a cost-effective option when extreme precision isn't necessary. Less stable than bearings with forged, one-piece housings, they're good for hand-cranked systems, gravity feed conveyor rollers, and other low-speed applications. The sleeve inside is made from naturally slick plastic, so there's no messy grease to drip off, wash out, or collect dust. With no moving parts, sleeve bearings stand up to grimy environments better than ball bearings. However, with more friction generated, they're less effective at high speeds.