58mm ND Filters ND1000 (10 Stops) Lens Filter 28 Multi-Layer Coatings Waterproof Scratch Resistant Super Slim for Camera Lens (Nano-X Series)

SKU: KF01.975

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hello, this is not variable nd filter, it just nd1000 filter, it is 10stop, 
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Your camera's lens thread size will be marked somewhere on the lens barrel or printed underneath your lens cap. This number is always preceded by a "ø" (diameter) symbol. 
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No I don't think it will fit any Gopro not unless it's specifically made for it. This size fits a 58mm lens thread and the Gopro has a much smaller size lens.