Universal connecting shaft coupling is made of 45# steel, then plated, more solid, wear-resistant, durable, small and exquisite, long service life. Fastener Type:Coupling. Thread Size:M3. 2-2mm，2-2.3mm，2.3-2.3mm，2.3-3mm，2.3-4mm，3-3mm，3-3.17mm，3-4mm，3-5mm，3.17-3.17mm，3.17-4mm，4-4mm，4-5mm，5-5mm，5-8mm，6-4mm，6-5mm，6-6mm，6-8mm，8-8mm，8-10mm，10-10mm,3-2mm，4-2mm,Hex Wrench + Set Screw.
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