Arlo's smart doorbell doesn't have a security camera

The Arlo Audio Doorbell costs $80 but also requires an $80 Arlo Base Station to operate -- for a $160 total cost. 

This is the Arlo Base Station. It plugs into your Wi-Fi router. 

The Audio Doorbell sends push alerts to your phone whenever it detects motion -- or whenever someone rings the buzzer.

This doorbell runs on two AA batteries. 

It can also be hardwired to work with an existing doorbell chime.

The Arlo Chime, sold separately for $50, acts as your doorbell chime if you don't hardwire the Audio Doorbell.

Several Chimes can be purchased for larger homes to make sure you hear your doorbell wherever you are.

The Audio Doorbell works with Arlo security cameras, too. The idea is that you'd use the doorbell for two-way audio conversations and the camera to see who's at the door.

The Arlo Audio Doorbell is a bit of a departure from its main competitors like Ring, Nest, August and SkyBell, due to its audio-only design.