The Siemens 3VA2040-5HN36-0AA0 is a SENTRON molded case circuit breaker (MCCB) in the 3VA2 line, rated 40 A continuous at 40 °C and holding that full 40 A all the way up to 70 °C — no derating curve to chase across the ambient range of a warm panel. Three poles, electronic ETU350 overcurrent release. The ETU350 gives you adjustable thermal-magnetic or electronic protection curves depending on the variant; here it's configured for line protection, meaning it's set up to protect cable and bus runs rather than a specific motor or transformer. Breaking capacity is the headline number that decides whether this breaker clears a fault without welding its contacts or venting arc gas into the enclosure: 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 3 kA at 690 V. Front panel carries IP40 protection.
That 105 mm width (about 4.13 inches) is the standard 3-pole MCCB footprint for this class — it occupies three 35 mm DIN-rail modules plus a bit of air for the arc chamber. The listing shows a motor drive as an optional extension — meaning this breaker can accept a remote motor operator for electrical closing/tripping, which is useful when you need to cycle the breaker from a PLC or SCADA without putting an operator in front of the arc flash boundary.