5/16 Domestic M14x1.5 Surface Seal Inverted NutThe 5 16 Domestic M14x1. 5 Surface Seal Inverted Nut is a precision machined fitting used in brake and fuel systems. This nut is designed to secure a 5 16" brake line to an M14 x 1. 5 threaded fitting with a surface seal (usually an integrated rubber or elastomeric seal). It provides a leak proof, secure connection in domestic automotive and hydraulic applications, particularly in brake line installations for American made vehicles. Specification