These Aopin 6003Z bearings are seriously smooth operators! With dimensions of 0.67 inch inner diameter and 1.37 inch outer diameter, they're perfect for skateboards, inline skates, scooters, and all kinds of wheeled equipment. The double rubber seals are awesome because they keep dirt, dust, and moisture out while keeping the lubrication in - way better than iron seals for most applications. Made from durable high-carbon steel, these bearings can handle both radial and axial loads like champs. The grease reference speed of 16,000 rpm means they'll keep you rolling smoothly at whatever speed you're going. No burrs or rough edges - just clean, precision manufacturing that makes installation easy and performance reliable. Whether you're replacing worn-out bearings on your skateboard or upgrading your scooter's wheels, these 6003Z bearings deliver professional quality without the professional price tag. The 2-pack is perfect for most projects, and they work great for electric motors, pool pumps, lawn mowers, and wheelbarrows too. Seriously, your wheels have never rolled this smoothly!