SN1835f1.8-Z Zoom Gear ~for Sigma 18-35mm F1.8 DC HSM | AZoom gears allow access to the mechanical zoom function of supported lenses. Use of this gear may require the use of additional port extensions or adapters. Check the Port Chart for more details. This zoom gear is for the Sigma 18 35mm F1. 8 DC HSM A (Nikon mount) lens. Product Manual PDF This item is non returnable, non refundable, non cancellable, and may be subject to extended lead times as it is manufactured on demand. We always do our best to