What's in the box:

Aibecy X-Axis Synchronous Belt Stretch Straighten Tensioner Timing Belt Adjustment Device Aluminum Profile Compatible with Creality Ender-3/CR-10 Series 3D Printers (Standard)

Features:
Made of high quality aluminum alloy, durable and wear resistant.
Surface anodizing treatment, effective protection.
Easy to operate, simple combination installation and use.
Already installed, you don't need to install it yourself.
Compatible with Creality Ender-3/CR-10 Series 3D Printer.

Specifications:
Color: Black
Material: Aluminum Alloy
Surface Treatment: Anodic Oxidation
Compatibility: Fit for Creality Ender-3/CR-10 Series 3D Printer
Item Size: 8 * 2.4 * 1.9cm/ 3.1 * 0.9 * 0.7in
Item Weight: 57g/ 2.0oz

Packing List:
1 * Belt Tensioner