Features and Benefits:

• 22 etched blades cover the complete range of sizes from 0.004" to 0.0.27" (0.10 to 0.69mm)
• Blade length: 3-6/16"

It's very important to measure the spark plugs gap.  With this gauge it checks clearance measurements with a 0.002" range.  The stepped blades quickly indicate if clearance falls within the specified range.  Simple  and made for everyday use!