The 5SL6140-6CC: The 40 A rating at 230/400 V is the continuous current the breaker carries without nuisance tripping at 30 °C ambient. B-curve is the fast-trip characteristic — it holds through mild overloads but opens quickly on a hard short, which is what you want when the downstream wiring and load don't have a big magnetizing inrush. If your service entrance feeds a higher fault level, you'd step up to a 10 kA or 25 kA rated MCB in the same 5SL family.
Snap-on DIN rail mount, 1-pole width (roughly 18 mm per pole). The 5SL series uses a standard modular footprint, so it clips into any 35 mm DIN rail enclosure alongside other Siemens or third-party modular devices. The B-curve designation is printed on the front face alongside the rating — no confusion during panel build or field swap. Spring-cage terminals accept 0.75 to 25 mm² conductors; torque to 2.5 Nm.
RoHS compliant since June 2013. REACH candidate-list declaration is available from Siemens. Product class B means the return is restricted; coordinate with your Siemens channel partner before sending anything back.
Group code P310 and product group 3819 are Siemens internal cataloging identifiers that map this breaker to the Basic Devices family. They're useful when cross-referencing against a legacy BOM or Siemens spare-parts portal.