Personal 10 Modes Quiet Waterproof Bullet Tool Powerful Mini Stick for Pleasure, Handheld Travel Pocket Personal Bullet Portable Soft Toys Massage Ball for Body Relax（Black）

This is more solid and heavy than I would have thought. And perhaps because of this, it's pretty 'powerful'. On the downside the material can be a little bit cold at first.

The literal definition of "small but mighty" haha. This thing is tiny but the motor is crazy strong.