Spark Plug Indexer; Hex Head Design; Flat/Taper Seat 14 mm Spark Plugs; Black Anodized; • High-compression drag race engines require "indexing" of spark plugs to prevent contact between piston dome and ground wire of the spark plugs • Moroso's "Indexer," designed for both flat and taper-seat 14mm spark plugs, enables selection of spark plugs that will not make such contact • Once a given plug is selected (placed in a cylinder head and found to have the correct ground wire position), it is placed in the Moroso Plug Indexer and the position of the ground electrode marked on the black anodized surface • Marking provides a reference for checking other plugs to be used in the same cylinder • The hex-head design allows it to be held in a vise