It's a 3-pole thermal-magnetic breaker with a C-curve, rated 63 A at 50 °C per EN/IEC 60947-2. The C-curve means magnetic trip occurs between 5 and 10 times rated current — here, the ledger confirms 8.5 x In ±20 %, so it clears moderate inrush without nuisance tripping on motor or transformer starts. That 63 A rating at 50 °C is the real-world thermal limit; ambient derating above that temp is on you, but the base number is solid for a 35 mm² cable feed.
Breaking capacity is 20 kA Icu at 240 V AC phase-to-phase, 10 kA at 415 V, and 6 kA at 440 V — all per EN/IEC 60947-2. The Ics (service breaking capacity) is 75 % of Icu at each voltage level: 15 kA at 240 V, 7.5 kA at 415 V, 4.5 kA at 440 V. If your panel's SCCR is higher, you'll need upstream current-limiting fuses or a higher-rated breaker.
Snaps onto 35 mm symmetrical DIN rail. The 54 mm width (3 x 18 mm per pole) and 73 mm depth mean it fits standard distribution enclosures without crowding the gland plate. Tunnel terminals accept 1.5 to 35 mm² — flexible with or without ferrule, or solid. The IP20 finger-safe terminals are fine for enclosed panels but not for wet environments. Busbar and distribution block compatible top or bottom, which simplifies daisy-chaining in multi-pole layouts.