You can pick up these filters here  https://mavenfilters.com/aff/nickpage/

It was time... my previous filter system had let me down for the last time... dropped filters, easily broken filters and Magnets that couldn't hold fast to a lens. These new Maven filters are not only built better, with better materials, but the magnets are strong and positive, color coded for ease of use, the same price once they go to retail... but they are independently owned... The color coded design makes these fast and easy to grab the filter you need. In my opinion they are a better filter in every way.