The Siemens SENTRON 5TT5531 is a remote control switch — a latching relay design that lets you switch a load remotely via a control signal, with the switched state held mechanically so it doesn't drop out on control-power loss. It's rated 16 A at 230 V AC, with that same 16 A holding at cos φ 0.6, meaning it handles motor or inductive loads without derating. The single-pole normally-open contact (1 NO) switches the line; the coil accepts both AC and DC control voltages, giving flexibility in mixed-voltage panels.
One modular width unit (18 mm) keeps the panel fill factor tight. Mounting height is 90 mm, installation depth 55 mm, so it clears most shallow enclosures. The 230 V AC control supply is the nominal; minimum pickup is also 230 V, so verify your control transformer isn't sagging under load.