Phoenix Contact ST 2,5 BU is a single-level spring-cage feed-through terminal block rated 2.5 mm² in blue, typically used for neutral conductors. It accepts solid conductors from 0.08 to 4 mm² and stranded conductors from 0.08 to 2.5 mm², with a rated current of 24 A at 800 V. The 5.2 mm wide housing snaps onto 35 mm DIN rail and offers an Ex e explosion-tested variant for hazardous-area cabinets. Operating temperature spans -60 to 110 °C, suiting industrial control panels, distribution boards, and machine-building applications.