Magnetic Slim Step-Up Adapter

In the past, the sea spray had ruined my CPL/ND filters when I did not put on a protective filter in the front. I bought this magnetic protect/adp for the protection of the ND / CPL magnetic slim kit from sea spray or desert sand because the kit doesn't have a perfectly matched protective filter. The problem is that this dual purpose protect/adp must have been designed only for the lens, thus having a thicker threaded section. For my usage, it would create a larger gap when stacking in front of other slim filters. Not only can water and sand get in easily, but the thicker treads also has weaker magnetic power, which could fall off easily if not careful. I wish you could design and add a magnetic slim protective filter (without the threaded section) to the kit that can be used to protect the other slim filters from harm. Regards, Ingjye Juan