The ABB 1SDA054212R1 is a circuit breaker accessory from the T4H250 platform, identified on the nameplate as 33H 250 TMA 125-1250 3P F F. It's a three-pole unit with fixed thermal-magnetic trip unit, adjustable from 125 A to 1250 A, intended for the Tmax T4H250 molded-case breaker frame.
The description string '33H 250 TMA 125-1250 3P F F' decodes: 33H is the ABB internal ordering variant, 250 refers to the frame size (250 A frame), TMA is the thermal-magnetic adjustable trip type, 125-1250 is the adjustable current range, 3P is three-pole, and F F indicates fixed front terminals. The T4H250 platform means it fits the Tmax T4 series breakers with a 250 A frame — a common platform in commercial and industrial distribution panels.