RAINPAL F075LFLH Brass 3/4" Female Bulkhead Fitting(Lead Free Compliant, Left Handed Nut) (6) Contain Less than 0.25% Lead, Lead Free Compliant, For more information about lead free complaint, please visit EPA.gov Inside is 3/4" straight pipe thread. Need 1-1/4 inch diameter hole to install. Fit up to 10mm thickness wall. Left Handed Nut (Reverse Threaded) for easy installation. Only lightly tighten the male 3/4" fittings(not included) for easy uninstallation. Now comes with recessed gasket, will not slip during installation