Analógový vstupný systém - With which products can I expand an audio kit from the Niko Access Control range?

The audio kit can be expanded maximally with:

• 1 internal audio unit: a compact surface-mounting telephone (10-511) or hands-free internal audio unit (10-520)
• 1 external audio unit
• 1 DIN-rail relay (10-830 or 10-831)