7 types of pulley bags Plastic gear bag DIY

A: tight fit B: loose fit
2A indicates that the central axis is 1.95mm; it fits closely with the 2mm optical axis and rotates with the optical axis.
2B indicates that the central axis is 2.05mm; loosely matched with the 2mm optical axis and freely rotate on the optical axis.
62A: 6: diameter 6MM, central axis is 1.95MM
132A: 13: 13MM diameter central axis is 1.95MM
102B: 12mm pulley + 102B gear combination
Inner hole 2.05mm, loose fit (large wheel outer diameter 14.6mm / small wheel outer diameter 5.75mm)
122B: pulley diameter 16MM gear 12 teeth 0.5 module inner hole 2.05MM loose fit