The thermal-magnetic trip mechanism handles overloads via a bimetal strip and short-circuits via an electromechanical solenoid, so you get both time-delayed and instantaneous protection in one package.
Trip Curve B — what that means for your panel
Curve B trips at 3 to 5 times rated current (60–100 A for this 20 A breaker). That's a narrow instantaneous band, so it clears low-level faults fast but avoids nuisance tripping on small motor starts or capacitive loads. If your circuit has higher inrush — say a larger motor or a bank of switching supplies — you'd want Curve C (5–10× In) or Curve D (10–20× In). The S800S family includes those variants, but this B-curve unit is the right call for general-purpose distribution where the loads are mostly resistive or have modest inrush.
Panel integration
The 3-pole footprint matches the S800S family's modular width — roughly 3 × 17.5 mm per pole. The toggle handle and clear status window give a quick visual on the trip state without opening the panel door.