4Pcs ND Filter Set ND2 ND4 ND8 ND16 Neutral Density Filtors for Digital Camera | eBay
Amazon.com : NEEWER 67mm Magnetic Variable ND Filter ND2-ND32(1-5 Stops) with Magnetic Adapter Ring, HD Adjustable Neutral Density Filter with Water Repellent Double Sided 30 Layer Coatings, No X Cross : Electronics