Sold Out Quick view NGK NGK Ruthenium HX Spark Plug Box of 4 (LTR6BHX) - 90495 Compare $49.99 NGK Spark Plugs (U.S.A.), Inc. is the largest OE supplier and manufacturer of spark plugs for domestic and import vehicles in North America. Its OE legacy, unsurpassed quality and leading vehicles in operation coverage reinforces NGK as The Ignition... Currently Out of stock. On order! Currently Out of stock. On order!