FOR HIGHER DEMAND ON ND LEVEL AND PREVENTING X CROSS PATTERN: When a variable ND filter is mounted on a wide-angle lens and adjusted to its more higher stop, it will produce X pattern, which is related to the optical refraction design principles of the lens. H&Y's exclusive solution is to stack a magnetic ND filter at the front to mitigate this issue | CHANGING FROM 1-5 STOPS TO 9-13 STOPS: The method of stacking RevoRing ND400 filter can meet photographers' demands for higher light reduction, making it easier to achieve specific shooting effects | 3 IN 1 FILTER SETS TO 6 IN 1 FILTER SETS: The individual RevoRing variable ND & CPL filter features are variable ND, polarizer and variable ND + polarizer functions. When combined with the RevoRing ND400 magnetic filter, the overall functionality is expanded. Building upon the features of the RevoRing VND&CPL, additional options include variable ND + ND400, circular polarizer + ND400 and variable ND + polarizer + ND400, totaling six functions | SPECIAL NOTE: When you do not need to use the RevoRing magnetic filter, simply use your thumb to push from the side of the circular magnetic filter, it will detach from the revoring variable ND + CPL filter | WARRANTY AND LIFETIME SUPPORT: H&Y lens filters ensures lifetime warranty and sales support. We value your suggestions on our products, which assist us in continuously improving and innovating for the future