Timing belt: The timing belt is made of premium rubber, durable and flexible. It's designed specifically for linear motion, high positioning accuracy. Round tooth guarantees that the belt tooth fits smoothly. Pulley: It's used with timing belt, convenient to use. 20 Teeth contact with the belt, that minimizes the of the belt slipping. Locking Spring: With the springs, you can add the right tension you need and make your prints much more precise. Mounting Block: The mounting block is used in open belt buckles for 2GT belt (and some other models). Make that the gearbox is and free from loosening. Compatibility: compatible with most 3D printers. Attention: , keep from children GT2 Timing Belt: Type: GT2 Material: Rubber Shape: Open timing belt Length: 5m Width: 6mm Pitch: 2mm GT2 Pulley: Teeth: 20 width: 16mm Diameter of bore: 5mm Groove width: 7mm Flange: Dual Material: Aluminium Idler: Teeth: 20 Diameter of bore: 5mm width: 8.5mm Material: Aluminium Timing Belt Tensioner Spring: Material: Stainless steel Color: Silver Inner Diameter: 5mm Wire Diameter: 0.8mm Circle number: 7 Suitable for 6mm timing belt added the right amount of tension to the belt Mounting block: Material: Aluminum Teeth width: 0.85mm Teeth depth: 0.9mm Pitch: 1.1mm (the groove part) Size: 9 x 40mm, the middle hole is mounting hole. colour:black Material:Aluminum and rubber Package Contents: 1 x 5M GT2 Timing Belt 4 x GT2 Pulley 4 x Idler wheel 4 x Tension Spring 8 x Screws 2 x Mounting block 1 x Hex Wrench Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is 1-3cm.