Spark plug having a plurality of vertical ground electrodes and

Spark plug having a protective titanium thereon, and methods...

Spark plug having a spark discharge portion with a specific comp

Spark plug having a specific structure of noble metal tip on...

Spark plug having a welded electrode and the method of...

Spark plug having an erosion resistant tip

Spark plug having arc-shaped precious metal chip and method of p

Spark plug having center electrode with columnar portion and...

Spark plug having enhanced capability to ignite air-fuel...

Spark plug having ground electrode having cross section with...

Spark plug having ground electrode including precious metal...

Spark plug having ground electrode made of NI alloy and...

Spark plug having heat- and corrosion-resistant surface

Spark plug having horizontal discharge

Spark plug having horizontal discharge gap

Spark plug having improved configuration of ground electrode...

Spark plug having improved consumption resistance

Spark plug having iridium containing noble metal chip attached v

Spark plug having iridum alloy tip, iron-based alloy tip...

Spark plug having noble metal tip