Fitment: The PQY spark plug gap tool is for most of 14mm 12mm 10mm 16mm standard spark plugs. But not for 18mm thread . Spark plug gapping tool :the tool is made of high quality aluminum with matte texture,allows you to adjust spark plug gap easily and quickly .Just place your spark plug onto the spark plug gapper and then use your desired feeler, then screw the knob slowly until get your desired gap thickness. Tip for adjusting gap: Some spark plugs electrode will spring back when adjust gap. So if your gap target is 0.44mm ,we suggest to use 0.42mm, this way when it spring back you will get it to 0.44mm. 32-Blades Feeler Gauge:the feeler gauge is made of high quality manganese steel,with measurement range from 0.0015inch (0.04mm) - 0.035inch (0.88mm).Including one 0.010Inch(0.25mm) brass blade to use with electronic ignitions. Attention:this spark plug gap tool can not work for long reach or short reach plugs spark plugs, please check your spark plug’s size before purchase . Simple steps for easy installation:
1. Simply place your spark plug into the gap tool.
2. Use your desired size feeler gauge for gap thickness.
3. Turn the knob with the feeler gauge in place till the side electrode compresses to the desired gap thickness.

NOTE: Some spark plugs electrode will spring back - This is normal for some spark plugs
If your gap target is 0.44mm we suggest to use 0.42mm this way when it spring back you will get it to 0.44mm.
Please note that will vary on every spark plug brand, manufacturer, material of the spark plug.