Find the family.
Then the exact fit.

6–2,600 A common industrial range; 24 Vdc to 690 Vac coils/systems; AC-1/AC-3/DC utilisation categories

1–16 contacts common; 5–20 A contact ratings; coil/supply from 5 Vdc to 240 Vac/dc; plug-in or DIN rail

Milliseconds to days/weeks; 12–240 Vac/dc; multifunction, on-delay, off-delay, interval and star-delta

mA electronic fuses through 6,300 A power fuses; 32–1,500 V; gG/aM/aR/semiconductor/HRC classes

16–6,300 A; up to 1,000 Vac/1,500 Vdc; 2–4 pole, fused/non-fused, enclosed/open

16/22/30 mm operators; momentary/maintained; 1–10 A contacts; IP20–IP69K and Ex variants

16/22/30 mm; 2–5+ positions; key/lever/illuminated; maintained/spring return

8–30 mm panel indicators; 5–690 Vac/dc; LED/neon; single/multicolour and hazardous-area

0.14–240 mm²; roughly 5–415 A and 250–1,500 V; screw, spring, push-in, bolt and barrier

Signal mA through power >1,000 A; 5–1,500 V; circular, rectangular, heavy-duty, data and hybrid

15/32/35 mm rail families; 0.5–2.3 mm thickness; slotted/solid steel, aluminium or stainless

5 W–1 kW+ per module; 5/12/24/48 Vdc outputs; 1/3 phase input; redundant/hot-swap variants

About 50×50×30 mm through >2,000×1,500×800 mm; IP54–IP69K; polymer, steel, stainless, GRP and Ex

Wall boxes through multi-bay enclosures up to roughly 4 m high/long; IP20–IP69K; indoor/outdoor

Small machine panels through multi-bay lineups; 24 Vdc controls to 690 Vac power; climate-controlled variants

Small junction boxes through walk-in rooms; Ex d/e/p/t; gas/dust zones; aluminium, stainless or GRP

0.14–240 mm²; insulated/uninsulated; single/twin; DIN colour systems

1–200+ mm supplied diameter; 2:1–6:1 shrink ratio; thin/medium/heavy wall; adhesive-lined and busbar insulation

0.5–150 mm cable diameter or 0.25–240 mm² conductor range; clip, sleeve, heat-shrink, wrap and printable