Product FeaturesProduct Name : Linear Bearing; : LMK12UU;Material : Metal, RubberInner Diameter : 12mm/ 0.47";Outer Diameter : 21mm/ 0.82";Length : 30mm/ 1.2" Size : 31 x 31 x 5mm/ 1.2" x 1.2" x 0.2"(L*W*T);Mount Hole Dia.(Each) : 4mm/ 0.16"Hole Pitch : 21mm/ 0.83"(Center to Center);Color : Silver Tone, Black,Net Weight : 55g;The universal is great for you to replace the damaged in your devices to efficiency and save energy. Widely used in , industrial, low noise and high speed electric motors, construction machinery, automotive components, pumps, and machinery. Smooth moving, low friction, high rigidity and long life. Economical, easy to maintain replace. Package Content : 1 x Linear BearingNote:Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.