The Siemens SENTRON 3VA1050-4ED42-0HH0 is a 4-pole molded case circuit breaker (MCCB) rated for line protection, carrying 50 A continuous at 40 °C with no derating needed up to 50 °C — at 55 °C it still holds 49 A, and at 70 °C it's still good for 45 A. That thermal curve means you can run it near its nameplate in a warm panel without dropping frame size. Breaking capacity is the headline: 121 kA at 240 VAC, 75.6 kA at 415 VAC, 52.5 kA at 440 VAC, and still 11.9 kA at 690 VAC. That's a high-interrupting rating for a 50 A frame — it clears serious fault current without cascading upstream, which matters when you're coordinating downstream feeders in a distribution panel.
Dimensions are 101.6 mm wide, 130 mm high, 70 mm deep — a standard SENTRON 3VA frame footprint. The 4-pole width is the same as a 3-pole plus one module; check your enclosure fill factor if you're replacing a 3-pole unit.
That covers most indoor electrical rooms and mild outdoor enclosures. The -25 °C minimum means it's fine for unheated shelters in temperate climates.