That's 100 A at 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, and 70 °C, all the same. Three poles, with phase failure detection built in, so it catches a lost phase before the motor cooks. Breaking capacity is 330 kA at 240 V, 242 kA at 415 V and 440 V, 187 kA at 500 V, and 3.7 kA at 690 V. The trip delay is adjustable between 4 s and 17 s, which gives you room to coordinate with downstream motor starters and avoid nuisance trips on inrush.
That 105 mm width is three-pole standard for the 3VA frame — it'll drop into the same DIN-rail or panel-mount cutout as other 3VA2100 breakers. The basic switch assembly is order code 3VA21107MN360AA0, which is the internal switching mechanism; you're buying the complete breaker here, not a kit. Max power loss is 10 W — that's the heat to vent in the enclosure.