Product Name: Mini Pure Copper Universal Joint Coupling Material: Pure Copper Outer diameter: 7mm Length: 12.8mm Hole diameter: 3mm-3mm, marked either ends of the outlet is 3mm, both can be linked to the 3mm diameter shaft Side holes are M2.5 hexagonal screws, a complete of two Each coupling will send 2 M2.5 mechanical device rice screws, each order will only ship 1 small wrench. Brass miniature universal joint is beautiful workmanship, copper, appropriate for quite a lot of miniature science mannequin transmission, resembling mannequin aircraft, antique sailboats, etc. Pack Quantity: 1Pcs