Which product is the best to preserve, prevent and eliminate wood decay fungi, and wood ingesting/destroying insects? They are all equally as effective. You just need to know which is best for your particular situation. I will go over three of the most popular sellers, Armor Guard, Cobra Rods, and Shell Guard. Armor Guard You should use this product to protect wood that has not been compromised with decay or wood destroying insects. The concentrated powder is to be dissolved in water, stir the solution until it is clear and all powder is dissolved. You may then apply it with a low pressure sprayer.This must be applied to bare, clean, dry wood. Cobra Rods Unlike Armor Guard, Cobra Rods can be used after the wood is finished. The rods are used as a spot treatment to eliminate active decay and fungi. The chemical complex will activate once the rods are inserted into the wood. Moisture in the wood is the activator, and will continue to eliminate decay fungi, and prevent it for a good 8-10 years. Shell Guard Shell Guard is available in a concentrate or ready to use formula. Shell Guard will provide protection from, and eliminate existing wood destroying/consuming insects, and wood decay fungi. It must be applied on bare wood surfaces in order for it to impregnate the wood fibers with the active borate solution. You may drill a hole(s) in affected area(s) and inject the solution, you may then plug the hole and make it blend with the surface using Energy Seal or a comparable product. Shell Guard Concentrate, and Shell Guard RTU are both available in 1 gallon, 2.5 gallon, and 5 gallon containers.