You can purchase the Ring Alarm Pro as a complete system or get the base station ($249.99) and sensors you need separately.

Designed for apartments, condos, and small homes, the five-piece Ring Alarm Security Kit comes with a base station, a keypad, ...

This Alarm kit comes with a base station, a motion detector ... you’ll need to subscribe to the Ring Protect Pro plan. This subscription also unlocks smart home integration with devices like ...