It's here! 
The NiSi P1 filter holder with polariser and 3 stop medium graduated neutral density filter for you smart phones. 
It allows you to take your phone photography to another level. The 3 stop medium GND helps balance your exposure and the polariser will help bring out the colours, give more detail in the skies and cut through those unwanted reflections. 
Filter Holder for the NiSi Prosories P1 System 
Includes filter holder, phone clip, circular Polarizer, 3-stop medium Grade filter, and soft storage bag 
Filters are 40mm wide and 1.5mm thick 
Made of the Same Optical Glass as Regular NiSi Filters (H-K9L) 
Filter holder rotates independently of the phone clip for optimal Grade and Polarizer positioning.