K&F Concept Step-Up Ring 72-82mm Magnetic Please note: This magnetic adapter ring is only compatible with K&F CONCEPT magnetic filters. It is not compatible with filters from other companies. It is not suitable for screw-in filters. After purchasing this new, I tried attaching it once, but it didn't fit my K&F orange-knobbed magnetic filter set (82mm), so I ended up buying a regular step-up ring instead. I am selling this one. Please be very careful about compatibility. There is a crease on the box from when I took it out.