5.5 2.1mm Female Base: Each connector tip can plug to a 5.5x2.1mm male connector, such as 5.5 2.1mm laptop power bank, 5.5 2.1mm AC adapter. The female head of the 34 plug set is 5.5 2.1mm. (The interface of the power adapter DC power cord you use needs to be a 5.5 2.1mm male connector, or use a 5.5 2.1mm power cord to use with this set).
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