<h3>Key features</h3><ul> <li>20mm 0.79inch SBR20 UU ball bearings sliding blocks, made of aluminum alloy and bearing steel, heavy duty and sturdy</li> <li>High Quality - With excellent motion ball, it moves smoothly with low friction. You can use it for a long time.</li> <li>Size - Shaft diameter: 20mm. Overall size: 1.9” x 2” x 1.5”</li> </ul><p>Free shipping included. 30-day hassle-free returns.</p>