WINSINN GT2 Timing Belt Pulley 16 Teeth, 5mm Bore, for 10mm Width Belt - Ideal for Automation, Robotics, Precision Machinery (5-Pack)

These are exceptionally tight fitting listed as 6.35mm hole. Lightly pressed onto 1/4" shaft by hand. Wow what a nice surprise and fit. Quality is good all the way around. Excellent fit and function due to great dimensional control on manufacturing side.

Well made, working great. Does exactly what they're supposed to do.

This was part of my first step into physical modification of my 3D printer. these pulleys worked as expected, haven't slipped at all and yeah. they just work as expected.

Good quality pulleys. No fit or finish issues.

Used to build a couple of children’s projects like a model elevator, garage with moving door and an escalator.. Easy to attach a rod motor and rack to it. Worked well in all the projects.

The aluminum was not suitable for my project application.

Winsinn makes great fans, and now, they make great pulleys. I have put over 100 hours of printing on these pulleys without so much as skipping a beat. They're well made products and screw great onto any D shaft stepper motor. Fit and finish on these is nice- if a little shiny. Given how durable they are, I might just have to prematurely replace them and buy the black color. Finally- I would highly recommend a couple of drops of loctite blue (non permanent) on the grub screw threads before you set these onto your stepper motor for a guaranteed secure fit.

Working great just like I need them too. Easy to install for my project. The set screws hold their position well and not have any give to them even after raising them to just about the maximum height you can and tightening them. Will update later if something fails.