Tuned damper for stepper motor

I am looking for a Tuned damper to mount on the end of my stepper
motors.Does anyone know where I can buy a Tuned damper? Any and all
help would be appreciated. I have searched many stepper motor sites
but I have not found any mention of this kind of device. I have a 3
axis machine and all the stepper motors have a Tuned damper. I am
adding a rotary axis and I found that my stepper motor runs a lot
smother when I attached a damper to the end the motor.

Thank you,
AL