19 pcs Plastic Gears Kit Double Layer Cog Wheel Toy Model Car DIY Hole Dia 2mm

2A represents a central shaft of 1.95mm, which is tightly matched with a 2mm optical axis and rotates together with the optical axis. 2B represents a central shaft of 2.05mm, which is loosely matched with a 2mm optical axis and rotates freely on the optical axis.

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