IUGH666-1-41-20.0-01 is a three-pole hydraulic magnetic circuit protector from the IAG/IUG/IEG series designed for reliable circuit protection and accurate circuit control in international equipment applications. This unit features a 400Hz short delay characteristic (delay code 41) with a rated current of 20.0 amperes, standard toggle handle mounting, and series internal configuration with auxiliary switch (.110 quick connect terminals). The protector operates with an AC impedance of 0.006 ohms at 50/60Hz and 0.010 ohms at 400Hz, providing consistent performance across multiple frequency ranges. It is UL Recognized as a supplementary protector per UL STD. 1077 and CSA Certified, making it suitable for sensitive circuitry, automation systems, and equipment requiring IEC compliance. The black toggle handle with ON-OFF marking (-01 designation) enables clear operational indication in panel-mounted applications.