WonderPana 145 Core Filter Holder with Lens Cap for Sigma 14mm f/2.8 EX HSM RF Aspherical Ultra Wide Angle Lens Premium Grade Anodized Aluminum WonderPana 145 Core Unit for the Sigma 14mm f/2.8 EX HSM RF Aspherical Ultra Wide Angle Lens All metal build  two component collar system for secure mounting; Ultra wide angle construction to eliminate vignetting Ability to mount a variety of 145mm & 6.6" wide graduated filters: UV, CPL, MC-CPL, ND4/8/16/32; 0.6 & 0.9 Hard & Soft Edge, Reverse & Color Grads Doubles as a hood to help protect your lens from damage, scratches, fingerprints and the elements 24 Month Manufacturer Warranty