This is a magnetic camera lens filter compatible with the iPhone 17 Pro max from the brand K&F concept, which makes a variety of other camera gadgets. The whole set feels very premium, especially with the included hardshell case, lanyard and cleaning cloths. The lens itself comes with a magsafe adapter with a fairly strong connection, and it can fit over most cases as well (so you don't have to use your phone bare). The lens covers all 3 of the cameras and screws onto the adapter. There's also a cutout for the flash/lidar/speaker. Although this is designed for the 17 PM, it does technically fit over the older pro max models (however you would be covering up the flash). The build quality is overall really good.In terms of the lens itself, this is a variable ND (neutral density) type filter, which acts as like sunglasses for your phone lens to allow you to shoot with modes which will typically cause over exposure of the image if used without. I.e. it lets you shoot with wider apertures, or slower shutter speeds. There is a little bit of a learning curve where you have to just experiment with the iPhone's custom camera settings, and I think for the newbie to photography, probably this one won't feel like you are doing that much different to your photographs except making it a bit dimmer (and even that your automatic camera settings usually adjust for anyway). The good thing about this set is that K&F concept sells other lenses, including CPL only and combination ND with CPL, which you can swap in/out via the magsafe mount. I would recommend if you were to only get one to get the ND + CPL one, which also filters out polarising light and is good for minimising glare from the surface of water/ glass/windows etc.