What it is and where it sits in the series
The Molex 391002104 is the 4-circuit member of the Eurostyle 39100 series — a dual-row enclosed barrier terminal strip sized for chassis and panel mounting in industrial power distribution and control wiring. At 0.394 in (10.00 mm) pitch, it shares the same board footprint class as the 12-circuit 0391002012 but carries a lower circuit count and a 300V rating versus that variant's 600V ceiling. The 30A per circuit rating is held constant across both members, so the delta is purely positional and voltage-class — not current-carrying capacity.
Ratings that drive the fit check
The 4-circuit count is the primary fit parameter — a panel cutout or DIN rail layout built around the 12-position 0391002012 will not accept this strip without reworking the wire routing, since the two outer positions on the PCB footprint are absent. The 10.00 mm pitch confirms the board hole pattern; the 10-18 AWG wire gauge range tells you what ferrule or bare conductor the screw clamp accepts. Operating temperature runs -40°C to 105°C, so the strip handles the ambient extremes of a sealed industrial enclosure. The zinc-finished steel terminal screws are adequate for repeated torquing in panel wiring — not a concern for field replacement frequency unless the screw head is corroded in a humid environment.