JA1S-D3-AB-01-D-A-20-2 is a single-pole hydraulic-magnetic circuit breaker from Eaton's Heinemann J Series, designed for versatile protection in telecommunications, rail, marine, and mobile equipment applications. The breaker features a 20 A current rating with a medium-delay (Curve 2) trip characteristic, operating at 250 Vac with 50/60 Hz frequency capability. It incorporates a thermal-magnetic protection mechanism with a 1 kA interrupting capacity, providing reliable overcurrent and short-circuit protection. The device is designed to fit a standard 5/8" round or "D" shaped panel cutout with 6-32 mounting clips, offering flexible mounting configurations. This breaker is ideal for applications requiring moderate time delay before tripping, protecting transformers and electronic circuits from transient inrush currents while maintaining fast response to sustained faults.