NGK 3521 CR9EIX Iridium IX Spark Plugs 4 Pack

4 pc NGK 3521 Spark Plug CR9EIX Iridium IX The NGK 3521 CR9EIX Iridium IX Spark Plug is designed for compatible applications requiring performance-focused ignition. Featuring a durable iridium center electrode, the Iridium IX design delivers concentrated spark energy to promote strong ignitability, consistent combustion, and responsive acceleration. Built for demanding operating temperatures, NGK Iridium IX spark plugs feature trivalent metal plating for anti-corrosion and anti-seizing properties. This package includes 4 NGK 3521 / CR9EIX spark plugs. Application & Fitment Brand Part Number Spark Plug Number Series Fitment Requirement NGK 3521 CR9EIX Iridium IX Application must specify NGK 3521 / CR9EIX or a confirmed compatible equivalent Fitment Note: Spark plug compatibility varies by vehicle, motorcycle, powersport, engine, and other specific applications. Before ordering, verify that NGK 3521 / CR9EIX is specified for your application. Do not select a spark plug based only on physical appearance. Specifications Brand NGK Part Number 3521 Spark Plug Number CR9EIX Series Iridium IX Product Type Spark Plug Center Electrode Material Iridium Plating Trivalent Metal Plating Quantity 4PCS Reference Numbers Reference Type Number NGK Stock Number 3521 NGK Spark Plug Number CR9EIX Key Features Iridium IX Performance: Designed to provide enhanced ignition performance and durability compared with conventional spark plug designs in compatible applications. Iridium Center Electrode: Delivers concentrated spark energy to promote high ignitability and responsive acceleration. Consistent Combustion: Designed to promote effective fuel ignition in the combustion chamber for dependable engine operation. High-Temperature Durability: Iridium alloy construction provides durability under demanding combustion temperatures. Corrosion Resistance: Trivalent metal plating provides anti-corrosion and anti-seizing properties. Performance-Focused Design: Suitable for compatible applications requiring the performance characteristics of NGK Iridium IX spark plugs. Package Contents Item Part Number Quantity NGK Iridium IX Spark Plug 3521 / CR9EIX 4PCS Before You Buy Check Required Information Brand NGK Part Number 3521 Spark Plug Number CR9EIX Series Iridium IX Quantity 4 Spark Plugs Application Verify the exact engine/application and required spark plug number before ordering Spark Plug Gap Check the required gap for your specific application before installation Why Choose NGK Iridium IX? Iridium Technology Iridium center electrode provides concentrated spark energy for dependable ignition performance Ignitability Designed to promote effective ignition and responsive combustion in compatible applications Heat Resistance Durable iridium construction is designed to withstand demanding combustion temperatures Corrosion Protection Trivalent metal plating provides anti-corrosion and anti-seizing properties Installation Notes Confirm NGK 3521 / CR9EIX is correct for your specific engine or application before installation. Check the spark plug gap before installation. Although these spark plugs are pre-gapped for general use, the required gap may vary depending on the specific application. If gap adjustment is required, use an appropriate spark plug gapping method and take care not to damage the fine iridium center electrode. Install spark plugs only when the engine is cool. Avoid dropping or damaging the spark plug electrode and ceramic insulator. Thread each spark plug carefully into the cylinder head to help prevent cross-threading. Tighten the spark plugs according to the engine or equipment manufacturer's specified installation procedure and torque. Important: These spark plugs are pre-gapped for general use; however, the correct spark plug gap depends on the specific application. Always verify the required gap and NGK 3521 / CR9EIX fitment before installation.