The Siemens 5SL6004-7KL is a SENTRON miniature circuit breaker (MCB) in the compact 1-module-width format — 18 mm wide, 76 mm deep, 90 mm tall, so it snaps onto standard DIN rail and leaves room for the next breaker in the row. Rated 4 A at 30 °C, but that number drops as the panel warms: 3.84 A at 40 °C, 3.76 A at 45 °C, 3.67 A at 50 °C, 3.59 A at 55 °C, and 3.5 A at 60 °C — so if your enclosure runs hot, size up one step to keep the breaker from nuisance-tripping on a 4 A load.
Rated for AC only, 250 V max per phase, overvoltage category III, pollution degree 2 — typical for fixed-installation switchboards and sub-distribution boards. Compliance documentation: halogen-free and silicon-free construction, IP20 with conductors connected, touch-protected terminals, vibration-resistant per IEC 60068-2-6 — meets the usual RoHS/REACH expectations for European-marketed gear.
One modular width (18 mm) means it occupies a single slot — no need to rearrange neighboring devices when swapping in a panel that was laid out for a similar 1-pole MCB.