Earl's new adapter fittings are ideal for installing an after-market oil pressure gauge on GM LS engine swaps. These fittings screws directly into the M16 x 1.5mm oil passage on the rear china wall of the GM LS engine block. Options are available to fit most after-market sending units or mechanical gauge hoses (1/8" NPT female, -3 AN male, or -4 AN male). Black anodized 2024-T8 aluminum construction. Made in the USA.