Steve,
The wire seals are available at most West marine stores. They are typically in the electrical isle where the different switches and whatnot are. They are about $12, and come with 3 different rubber donuts to fit different wire sizes with the proper compression on the wires for the seal. I think they fit wires up to .250". The plug that my Eagle Fisheasy-2 uses is the largest that will fit through the top nut, which is the only drawback I have found with this item. The compression seal is top notch, but you're limited on the diameter of what you want to seal because of it also. Hope this helps
PerryC