The 431600103: The 18 A per circuit is the headline rating. The 7.50 mm pitch gives enough copper trace width and creepage distance on the PCB to handle 18 A without excessive heating or voltage breakdown at 600 V.
Position Count vs. Siblings
The 431600103 carries 3 positions. The same-series 431600105 offers 5 positions at the identical 7.50 mm pitch, 18 A rating, and tin finish — the only difference is the circuit count. If your BOM calls for 3 power circuits, this is the match; if you need 5, the 431600105 drops into the same footprint class with the same electrical headroom. The 431600106 (6 positions) and the right-angle 431603106 (6 positions with board locks) extend the same pattern for higher circuit counts.