WonderPana FreeArc Essentials ND Kit-Rotating Holder, Cap, 6.6"x8.5".6SE Grad ND & 145mm ND16 Filters f/ Tamron SP 15-30mm Premium Grade, Anodized Aluminum, Free Arc Rotating Core Unit Fits Industry Standard 6.6" Wide Filters, up to 4mm Thick (such as Schneider Optics) 145mm x 1mm Standard Thread Enabled Included Finely Crafted, Heavy Duty Inner Pinch Lens Cap 24 Month Manufacturer Warranty