Filament bulbs are bulbs that can be used with or without a lampshade, unlike other Hue bulbs that are designed for use primarily with lampshades. Filament bulbs can be viewed straight on and look attractive even when displayed in a naked lamp.
The Filament bulbs can be used over Bluetooth without a Philips Hue hub using the Philips Hue Bluetooth app, but if you have an existing Hue setup, the bulbs can also be added in the traditional manner and paired with your other Hue lights.
The Hue Filament bulbs are LED bulbs that are available only in a warm white light (2100K, 530 lumens) with an amber coating. The bulbs can be dimmed, but there are no color options.
There are three Hue Filament bulbs that will be available in the United States starting in October. There's a traditional A19 bulb that will be available for $24.99, a ST19 tube that will be available for $27.99, and a G25 globe that will be available for $32.99.
For more on the new Filament bulbs, check out the Hue website.