I have used ND grad filters for years on my SLR and DSLR cameras. I love scenery photography as opposed to portrait so always looking to sort out the difference in the light between the horizon etc. I live near the sea les that 300m away and walk along the cliffs regularly and don't take my DSLR with me when walking the dogs but always have my iPhone so any unexpected scenes are normally captured using the iPhone. This ND grad filter will come in useful. It fits over the lenses of my iPhone and helps sort out the difference in the light. Once clipped on it is easy to rotate the bezel to the setting you want using your finger. You have to ensure that you do not go past each of the stops or you will get leakage. SO my advise is to check before shooting that you are at the required stop. The other great thing about this filter is that it unscrews from the clip holder and can be screwed onto my 52mm lenses..Bonus... All in all this is a great little filter that I will carry around with me when out walking the dogs. We have a dog walking bag which has Poo Bags and drinking water etc so it sits in the side pocket of the bag in its case. so it is always there if we get a lovely sunset or something really nice to photograph on the sea or beach.. Get little gadget well worth the money highly recommended... As soon as we get anything really nice I will update this with the images...