Dimensions: The diameter at both ends is about 9mm, the middle diameter is about 7mm, and the total length is about 20mm;
Parameter meaning: 2X3mm (means that one end is a 2mm hole, the other end is a 3mm hole, and 2mm and 3mm shafts can be connected)
Top wire size: M3 screws are included, and the steel shaft is fixed through the side top wire screw holes