It is rated 40 A at 50 °C, with four protected poles (4D) and the neutral on the left side.
The 40 A rating is at 50 °C ambient — if your enclosure runs hotter, you derate. The long-time pickup (Ir) is adjustable from 0.7 to 1.0 × In, so you can fine-tune the overload threshold to the actual load without swapping the trip unit. The thermal delay (tr) is fixed at 120…400 s at 1.5 × In and 15 s at 6 × Ir — that long band at 1.5× lets a moderate overload ride through without opening, which is what you want for a feeder with a mix of loads. The 4D pole configuration protects all four poles, with neutral protection set to 1 × Ir.
This trip unit snaps into a ComPacT NSX100 or NSX160 breaker frame — the same frame accepts ratings from 15 A to 160 A, so swapping a trip unit changes the breaker's rating without pulling the whole device off the DIN rail or mounting plate. The breaker itself mounts fixed (not plug-in or drawout), which is typical for distribution panels where you do not need quick swap-out. IP40 front-of-panel protection is standard; the rear terminals are live when the breaker is closed, so standard safe-isolation practice applies.