Vibration Motor 11.6×4.6×4.8mm
This tiny DC motor has a shaft with an offset mass that vibrates when it rotates. Motors like this are commonly found in cell phones and other devices that use vibration for tactile feedback. The motor has 1.5″ leads and is encased in a removable rubber sleeve that gives it flat surfaces for mounting and prevents it from chattering against whatever it is mounted to.
It is intended for operation around 3 V (2.4 V to 3.5 V recommended).
more info: https://www.pololu.com/product/2265