Guest 4018 grounding plate improves performance of electronics and reduces RF interface. Offers the best path for hull bonding without long runs of copper foil. Provides a direct, low resistance path for improved lighting protection. Deters electrolysis and galvanic corrosion. Sintered porous bronze sphere construction for maximum conductivity in a compact size. Low drag, non-fouling shape. Easy to clean with wire brush. Easy to install. Mounting hardware included. Use with SSB radio. 18 W x 6H x 1/2D. Mounting holes: 9-7/8 center to center, 3 top to bottom.