It carries a 40 A fixed thermal-magnetic overload (Ir=40 A) and a fixed short-circuit pickup at 10 x In (Ii=10 x In). The N conductor is protected at 100%, and the unit includes a nut keeper kit specified for a DC Power OEM in China.
In a panel with higher available fault current — say 36 kA or 50 kA — this breaker would need an upstream current-limiting device or a higher-rated frame. The fixed Ir=40 A and Ii=10 x In (400 A magnetic trip) make this a straightforward line-protection breaker for a 40 A feeder; no adjustment range to set.