Why a board-level input module in an SSR line
The G3TB-IAZR02P-100-240VAC: G3TB-class couplers bridge a low-power logic output to an SSR's input circuit. The 100–240 VAC in the suffix tells you the field-side switching range the module accepts, so it can be wired to whatever AC control source is already in the cabinet without adding a transformer.
Sourcing posture for a mature-line Omron module
On a mature part like this, the question isn't whether it can be found — it's how cleanly it can be quoted against a BOM line. Independent distribution channels carry the G3TB-IAZR02P-100-240VAC in small-to-project quantities, and current pricing is confirmed at RFQ time.