2 Plug Gap Gauges Spark Plugs Approximately 38mm in diameter, 3mm thick 2 Plug Gap Gauges Spark Plug Gap Gauge ☆Size: Approximately 38mm in diameter, 3mm thick, Inner diameter of hole 8mm ☆Weight: Approximately 16g ☆Surface: Inches inc display [.020-.100 INCHES] ☆Back: Millimeters mm display [0.6-2.4 MILLIMETERS] ☆By adjusting the plug gap, engine performance can be kept optimal Plug Gap Gauge Size: Approximately 38mm in diameter, 3mm thick, Inner diameter of hole 8mm Weight: Approximately 16g Surface: Inches inc display [.020-.100 INCHES] Back: Millimeters mm display [0.6-2.4 MILLIMETERS]