It's a current-production part, so it's still rolling off the line — no hunting through surplus bins yet.
Breaking capacity varies by voltage: 100 kA at 240 V and 400 V, 42 kA at 500 V, and 4 kA at 690 V. At 690 V, the 4 kA figure is the limit — if your fault current exceeds that upstream, you'll need a current-limiting upstream device. The fuse back-up ratings (gL/gG 63 A at 400 V, 50 A at 500 V, 40 A at 690 V) tell you the maximum fuse size that preserves coordination; oversize the fuse and the breaker takes more fault energy than it's rated for.
The M3 main contact terminals accept 2× (0.5 to 1.5 mm²) or 2× (0.75 to 2.5 mm²) solid or stranded wire — strip length follows standard Siemens practice.