Industrial Encoder Accessories: Encoder wheels and counter wheels are used with encoders to measure the position, speed, or direction of a rotating shaft or linear movement. Encoder wheels, typically made of aluminum alloy, have regularly spaced slots or holes around their circumference. As the wheel rotates, an optical or magnetic sensor detects changes in the pattern, calculating the shaft's rotation angle or linear distance. Counter wheels are similar but feature a tread or track that contacts the surface being measured. They're often used to measure the speed of conveyor belts or other linear movements. [Material] Made of aluminum alloy for durability and long-lasting performance. A great replacement part. Size Specifications: Thickness: 13mm/0.51inch Diameter: 50mm/1.97inch Bore Diameter: 6mm/0.24inch Color: Silver Material: Aluminum Alloy Package Contents: 1 x Encoder Wheel 1 x Key Note: Only the above package content, other products are not included. Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.