Product Description: UPR’s New Spark Plug Gapping Tool with Built-in Feeler Gauges Designed to save time and give you much more precise gaps. This is what engine builders you as they are telling you how critical your plug gap is. Our new plug gapper will allow you to gap plugs must faster and maintain gap accuracy between all your plugs. The days of banging your plugs against table corners or the side of the tool box to close the gap risking porcelain fatigue and chasing spark leakage. This incorporates a steel ball in the end of the shaft so it will not drag when you turn the adjuster handle. This is something 99% of the cheapo spark plug gapping tools do not offer. Feeler Gauge sizes: .010,.012,.013,.015,.016,.017,.018,.019,.020UPR’s Spark Plug Gapping Tool with Built-in Feeler Gauges Designed to save time and give you much more precise gaps. This is what engine builders you as they are telling you how critical your plug gap is. Our new plug gapper will allow you to gap plugs must faster and maintain gap accuracy between all your plugs.The days of banging your plugs against table corners or the side of the tool box to close the gap risking porcelain fatigue and chasing spark leakage. This incorporates a steel ball in the end of the shaft so it will not drag when you turn the adjuster handle. This is something 99% of the cheapo spark plug gapping tools do not offer.Available in 10mm, 12mm and 14mm spark plug thread sizes. 79-95 5.0 SBF, 96-04 4.6, 11-19 5.0 all use 14mm thread spark plugs.Feeler Gauge sizes: .010,.012,.013,.015,.016,.017,.018,.019,.020Product Features:* CNC Billet Aluminum* Black Anodized Finish* Feeler Gauges Included* Roller Ball Tip on Gapping Screw* Available for 10mm, 12mm, 14mm spark plugs – Select Above79-95 Mustang 5.0 14mm thread spark plugs96-04 Mustang/Cobra 4.6 14mm thread spark plugs05-08 Mustang GT 4.6 16mm thread spark plugs08-10 Mustang GT 4.6 12mm thread spark plugs *some 2008 use 16mm, coil will have 3L3E on it07-14 Mustang GT500 14mm thread spark plugs11-19 Mustang 5.0 14mm thread spark plugs* You are purchasing the Spark Plug Gapper for the thread size listed in the item title ** These work on any vehicles that use the Spark Plug thread size listed in the title *