-4AN Turbo Oil Feed Adapter Fitting 0.035" Restrictor Size(AN) :AN -4 , 7/16"-20UNF Size ( INVERTED FLARE ) :7/16-24 inverted flare Materials :Cooper Color :Yellow Restrictor (Hole Size) :0.9mm (0.035") Appropriate for ball bearing or non-ball bearing turbo use. Can also be used on GT25R/GT28R/GT28RS/GT30/GT35R where restrictor is needed.