Only compatible with K&F variable ND filter; NOT suitable for UV CPL fixed ND, black soft, or magnetic filter, etc. Silicone material: soft and smooth, skin-friendly, not easy to stain, dirt-resistant, and easy to clean Easy to use: directly put on, easy to take out, all-round protection filter, more secure. Shatter-resistant, anti-drop function, will not wear the frame and scratch the lens