What This 2-Circuit Header Is
The 41791-0849: This is a Molex KK 156 header assembly — a 2-circuit, single-row pin header with a 3.96 mm pitch and a friction lock on the housing. The '30 S' in the description indicates a 30 µinch selective gold plating on the mating area, which gives it a solid cycle life for repeated connect-disconnect in a harness. The friction lock holds the mating receptacle in place against light vibration, but it's not a secondary lock — for high-vibration environments you'd want a TPA or a positive latch.