What it is and where it fits
The Siemens 5SL6516-7BB is a SENTRON miniature circuit breaker with a 1P+N design — it switches both the phase and the neutral, with the neutral pole switching but not overcurrent-protected. Rated 16 A at 230 V AC with a C-curve tripping characteristic, it is sized for residential and light-commercial branch circuits where moderate inrush (motor starts, capacitor banks) is expected. The 6 kA breaking capacity per EN 60898 covers most domestic and small-panel fault levels. It snaps onto standard DIN rail, takes 2 modular width units (36 mm), and the 76 mm depth leaves room for wiring in a shallow enclosure.
What the ratings mean for your panel
The C-curve (tripping between 5 and 10 times rated current) means this breaker holds through the short-duration inrush of a motor or a bank of LED drivers without nuisance tripping, but still clears a hard fault fast. At 30 °C it carries the full 16 A; at 40 °C the rated current derates to 14.78 A, at 45 °C to 14.08 A, and at 55 °C to 12.74 A — so if the panel runs hot, down-rate the connected load accordingly. The 6 kA breaking capacity (per both EN 60898 and IEC 60947-2) is the maximum fault current it can safely interrupt; if your service entrance has a higher prospective short-circuit current, you need an upstream current-limiting device. The IP20 rating (with connected conductors) is standard for a DIN-rail enclosure — no washdown rating, so keep it inside a dry panel.