Sigma Will Provide a Chargeable Installation Service of the Rear Filter Holder FHR-11 for Sigma 14-24mm F2.8 DG HSM | Art (for Canon) and 14mm F1.8 DG HSM | Art (for Canon) – Photoxels
Keeping it small, using rear filters for the Sigma 14-24 f2.8 Art DG DN - DIY Photography