Expert Quality, used in conjunction with petrol compression testers enabling the compression tester to be connected when spark plugs are deeply recessed inside the cylinder head. Examples of recessed spark plugs can be found in but not exclusive to Nissan, BMW, Ford, Vauxhall, Saab, Renault and Honda engines.Contents:Long reach adaptor length - 200mm with external thread sizes - 14 x 1.25mm and 18 x 1.50mm, internal thread size - 14 x 1.25mmAdaptor extension length - 65mm with external thread sizes - 10 x 1.00mm and 12 x 1.25mm, internal thread size - 14 x 1.25mm