The Siemens 5SJ4204-8HG41 is a 2-pole miniature circuit breaker from the SENTRON 5SJ4 series, rated 4 A at both 30 °C and 40 °C ambient. That 4 A rating holds up to 40 °C, then derates to 3.9 A at 45 °C, 3.8 A at 50 °C, 3.7 A at 55 °C, and 3.6 A at 60 °C — so if the panel runs warm, the actual trip threshold drops accordingly. The 2-pole design (2P) switches both phase conductors; there is no neutral pole switching. The overvoltage category is 3 and the degree of pollution is 3, meaning it is rated for fixed installations inside an enclosure where transient overvoltages and conductive pollution are expected — standard for industrial control panels and sub-distribution boards.
The 70 mm depth (installation depth 70 mm) and 110 mm height fit standard distribution board cutouts.