When sourcing alarm annunciators, you must prioritize reliability and visibility. Key specifications include the number of alarm windows (points), which typically range from 4 to 128 points. Ensure the device uses high-intensity LED illumination for long-term durability and low power consumption. Crucially, verify the input signal compatibility, such as Dry Contact, Open Collector, or Voltage inputs, and check if the sequence of operation complies with the ISA-18.1 standard (e.g., Sequence A, M, or R) to ensure standardized alarm handling.