Radium SAE adapter fittings are available in 5/16", 3/8", and 1/2" sizes. They push-on and secure to most modern USA, European and Japanese fuel injection systems and are used to convert an OEM SAE Quick Connect connection. Vehicle Fitment: Universal Application Includes: (1) Adapter Fitting Full Description: These adapter fittings are available in 5/16", 3/8", and 1/2" sizes. They push-on and secure to most modern USA, European, Japanese, etc. fuel injection systems and are used to convert an OEM SAE Quick Connect connection. The unique Radium Engineering adapter (20-0290 and 20-0291) interfaces with a SAE Quick Connect male fitting in an ultra-low profile manner. The design uses a dual viton O-ring seal for a leak free connection. The retaining clip is held on with a stainless steel screw and is easily and quickly serviced. To determine the required SAE size, simply measure the outside diameter of the male fitting as shown in the photos. • 0.3125 = 5/16" • 0.375 = 3/8" • 0.50 = 1/2" Important Install Notes: Always lubricate the mating O-rings with a light amount of oil prior to installing.