EXPLORE SQUARE FILTERS | Connect any 67mm diamter lens to use with our 100mm Square Filter Holder System. FIND YOUR LENS SIZE | The diameter of your lens may be on the front or side of your lens and can look like: Ø58 or Ø58mm. Note: the focal length of your lens is not the diameter. DURABLE HARDWARE | Made from durable magnalium. Backed by our lifetime warranty. PLEASE NOTE | To connect your lens to our Square Filter Holder System, find the right Lens Adapter Ring and then connect to the 86mm Main Adapter. PLANT 1 TREE | This Urth product funds local communities to plant trees in areas affected by deforestation