The Size S00 footprint — 45 mm wide, 70 mm tall, 73 mm deep — fits tight enclosures without giving up switching capacity.
The 3RT2015-2AP02 carries maximum switching frequencies by duty class: 1,000 operations per hour at AC-1 (resistive), 750/h at AC-2 and AC-3 (motor starting/running), and 250/h at AC-4 (plugging/inching). The AC-3e rating matches the AC-3 figure at 750/h. These numbers tell you how fast you can cycle the contactor under load without overheating — for a conveyor line running a motor start every few seconds, the AC-3 750/h limit is your ceiling. The DC switching capability is broken out by voltage: 10 A at 24 V, 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V, and 0.14 A at 440 V. At 400 V AC it's rated 3 A. That's a wide DC range — useful for battery-backed systems or DC bus switching in a panel.
That's handy when you're shoehorning it into a crowded panel and the rail isn't perfectly vertical. Wire sizes accepted: solid or stranded 0.5 to 4 mm², or 2x (0.5 to 4 mm²) for daisy-chaining. Keep that in mind when laying out adjacent components.
That covers most indoor panel environments without derating concerns.