Graves Motorsports Smog Block Off Plates are designed to seal off the ports on the valve cover used by the air injection system (AKA smog pumps or AIS). Once these are capped off, the air injection system can be safely removed. Made from machined aluminum. Sold in pairs (except where noted). The air induction system (AIS) burns unburned exhaust gases by injecting fresh air (secondary air) into the exhaust port, reducing the emission of hydrocarbons. Once these are capped off, the air injection system can be safely removed. These Smog Block Off Plates are made from CNC'ed billet aluminum and feature the Graves Motorsports "G" logo. There are three reasons why you want to remove the air injection system from your bike: If you are using your motorcycle on a closed course (racing, track days, etc.) you will want to remove all unnecessary equipment from your bike for reduced weight and ease of maintenance.