That 300 mA rating means it is sized for fire protection or general equipment protection — not personnel shock protection, which typically requires 30 mA or lower. The 40 A continuous rating at 50 Hz matches a standard single-phase or two-pole branch circuit up to that load; the derated values at elevated ambient temperatures (37.2 A at 40 °C, 32 A at 70 °C) are per the datasheet and should be factored into panel thermal calculations. The insulation voltage (Ui) is rated 460 V, and the overvoltage category is III, so this RCD is suited for fixed-installation distribution boards downstream of the main breaker — not for equipment-level or transient-prone circuits. The surge current resistance is 1 kA, surge voltage resistance 4 000 V, which covers typical mains-borne transients in a commercial or industrial panel. The 2-pole design (2 modules wide, 71 mm) and instantaneous trip characteristic (no adjustable delay) mean it is a straightforward fit for a DIN-rail enclosure where you need a simple, non-delayed RCD.
Mounting position is any, fastening method is standard rail (REG), and the installation depth is 70 mm. Supply connection can be top or bottom. The device is not sealable, so tamper-evident sealing is not supported.