HELLA spark plugs are designed for durability, reliability and optimal performance. All HELLA spark plugs have copper core center electrodes that provide utmost heat dissipation and conductivity to maintain Stable operating temperatures. The metal shell of each plug is nickel plated to offer higher resistance against corrosion. The insulator is made of very high density silicon dioxide compound that gives maximum strength against vibration in the engine cylinder and also prevents current leakage during sparking. HELLA offers four types of spark plugs. HELLA Energy is an OE equivalent plug for spare part replacement, while HELLA Energy Pro lasts longer than typical OE plugs. The performance series HELLA Platinum and Iridium Pro offer ultimate performance and power over a longer service life, ideal for both spare part replacement as well as for car enthusiasts looking to upgrade their car performance.