GT2 16 Teeth 6.35mm (1/4") Timing Pully (6mm width) without a flat surface. This model contains a triple option to lock the pully in place. There are 3 nut slots to fit in "DIN 439 - M2,5 x 0,45" and 3 holes of 2.55mm diameter for a set screw "DIN 913 - M2,5 x 4" Teeth dimensions are taken from the web and should be accurate for 2mm pitch belt.
Keep in mind, you work with plastic, do not over tighten it,