The Siemens 5SL6440-6CC is a 4-pole miniature circuit breaker (MCB) from the 5SL6 Basic Devices family, rated 400 V with a 6 kA breaking capacity and a B-curve trip characteristic at 40 A. The 4-pole configuration (all poles switched, neutral as the 4th pole) is common for three-phase plus neutral distribution boards where you need full isolation on all conductors.
Product class B means return is restricted — contact your Siemens partner or distributor for return authorization.
The B-curve at 40 A is a common specification for general-purpose sub-distribution boards feeding lighting, socket outlets, or small resistive loads — not for motor circuits where a C or D curve would handle the inrush.