GT2 Bearing Aluminum Smooth
"This pulley works with 6mm wide GT2 2mm pitch timing belt, it will work perfectly with the GT2 pulley-belt sets we are sell. The idler is a good match for the 20T GT2 timing belt pulley driven by stepper motor.
This Dual Bearing Aluminum Idler Pulley is a simple and inexpensive solution.
Use M5 screws to mount this pulley.
1 x GT2 Dual Bearing Aluminum Smooth Idler Pulley