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Note 3 - Acquisition and Divestiture - Schedule of Pro Forma Information (Details) - Enercon Technologies, Ltd [Member] - USD ($) $ / shares in Units, $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2025 | Mar. 31, 2024
Revenue, net | $ 152,238 | $ 158,805
Net earnings | 18,322 | 18,022
Less: Net earnings attributable to non-controlling interest | 448 | 1,085
Net earnings attributable to Bel Fuse shareholders | $ 17,874 | $ 16,937
Common Class A [Member] |  |
Earnings per common share - basic and diluted (in dollars per share) | $ 1.36 | $ 1.27
Common Class B [Member] |  |
Earnings per common share - basic and diluted (in dollars per share) | $ 1.43 | $ 1.34

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