Guest 4008 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. For bonding, grounding and Loran use. 8 W x 2. 5 H x 1/2 D Mounting holes: 4 center to center.