The Siemens SENTRON 5SL5106-7CC is a 1-pole miniature circuit breaker (MCB) with a C6 tripping characteristic, rated for 125 V DC and a breaking capacity of 10 kA.
The C6 curve means the breaker trips at 5 to 10 times rated current (30–60 A magnetic trip), which is standard for moderate inrush loads like lighting or control transformers on a DC bus. The 125 V DC rating is the maximum operating voltage — verify your system voltage stays under that. The 10 kA interrupting rating at 125 V DC tells you it can safely clear a fault up to 10,000 amps without welding contacts or cascading upstream; that's a solid figure for a 1-MW DC sub-panel.
Its 18 mm width (1 MW) leaves room for adjacent modules in a crowded enclosure. The sealable feature allows lockout/tagout for maintenance isolation.