This chrome plated brass cable outlet has rubber grommets for watertight passage of 1/4" or 5/16" diameter cables (select size accordingly).

The mounting flange is 1-1/4" diameter and outlet extends only 5/8" from trailer. Attach with #4 screws (not included). 

The typical diameters of various coaxial cables are these:

• RG-6/U (double shieded) .270" (~1/4")
• RG-7 .320" (~5/16")