If your Connect Hub (Gateway) has only ALC Wireless Made Simple on the top, then your Hub can support up to 24 total sensors.
If your Connect Hub also has Connect on the top, it can support up to 36 total sensors.
Compatible sensors are:
• AHSS11 Door/Window Sensor
• AHSS21 Remote Control
• AHSS31 Motion Sensor
• AHSS41 On/Off Power Switch
• AHSS51 Indoor Siren