The Siemens SENTRON 5SY4316-6CC11 is a 3-pole miniature circuit breaker rated 16 A at AC, with a B tripping characteristic and a 10 kA breaking capacity per EN 60898. It's designed for railway applications and general industrial use, with a pollution degree of 3 and overvoltage category III — meaning it handles the transient environment of a control panel fed from a distribution board without derating.
The 16 A rating holds at 35 °C ambient; at 40 °C it derates to 15.04 A, at 50 °C to 14.02 A, and at 60 °C to 12.91 A. That's enough for most secondary panels fed from a transformer with a reasonable fault level. If your available fault current exceeds 10 kA, you'll need an upstream current-limiting device or a breaker with a higher SCCR.
Mounting position any, so you can orient it sideways or upside-down in a tight cabinet without derating. The terminals are combined top and bottom, accepting conductors for the rated current. Touch protection is built in.