E/M~to 1/2 Thick Roof 58U NC Precision 50O Interface Low-Profile Interior Installation Self-Adjusting NMO Locking Nut Eliminates Guesswork and Decreases Installation Time All Brass and Stainless Steel Components for Maximum Reliability and Corrosion Resistance Non-Rotational Heavy-Duty Centering Washer Ensures Perfect Hole Alignment while Optimizing Non-Slip Clamping Pressure