NOTE:There is an error between the technical size and the particular length NOTE: Data parameters have error ± 0.1mm to illustrate :X2A X1.5A X2.5A 1.X : Number of teeth 2.A: tight with B: free with 0.8A shows the central axis of 0.75mm; 0.8mm of the optical axis, with a tight, rotates along with the optical axis. 1.5A displays the central axis of 1.45mm; 1.5mm of the optical axis, with a tight, rotates together with the optical axis. 2A shows the central axis of 1.95mm; 2mm of the optical axis, with a tight, rotates together with the optical axis. 2.5A shows the central axis of 2.45mm; 2.5mm of the optical axis, with a tight, rotates together with the optical axis. 3A shows the central axis of 2.95mm; 3mm of the optical axis, with a tight, rotates along with the optical axis. 2B represents the central axis of 2.05mm; and the optical axis of 2mm, loosely fitted, loose to rotate at the optical axis. Gear diameter = (number of tooth +2) * 0.5 ( mm) Modulus:0.5 d(Aperture) :1.95MM ,Tight tournament 2mm shaft D:27MM