ST21 (ST21 Spiral Filament Alexa Google Decorative Smart Bulb) is an RGB smart light bulb introduced by FEIT Electric. It is a product that not only can be operated through a smartphone and voice support, but also intuitively changed any color through the color wheel.
It looks like a classic filament bulb. However, LEDs are wound here, and you can turn them on or off via Wi-Fi, dimming, and schedule settings remotely through Amazon Alexa, Google Assistant, or Apple Siri.
The price is $19.99. There is also a prototype product called G30 as a similar model. Related information can be found here .