1Universal Tool: The gap tool is universal for 10mm 12mm 14mm 16mm spark plugs, as well as compatible with Ngk 6061, Ngk 5671A, Ngk BKR9EIX and similar spark plugs. 2Powerful Function: The spark plug gap tool could provide you with perfect gap every time, just place your spark plug onto the gap tool, extremely easy and convenient to use. 3Match to Use: The heavy duty spark plug caliper come with a feeler gauge, you can use with both to get your desired spark plug gap thickness, bring you more convenience. 4Spring Back Phenomenon: It is pretty common for some spark plugs electrode to spring back, if your gap target is 0.44mm, we suggest to use 0.42mm, then you can get it to 0.44mm when it spring back. 5Recommendation: If the metal spark plug gap tool gets wet, you can use compressed air to dry and apply lubricant (not included), to get high performance again.