From Jeffrey Tsai - As Xmultiple's Engineering Manager I would like to give you a complete answer with some background information.

(RJ Style Connector contact pins material is made of phosphors bronze by most connector manufacturers. The phosphors bronze material remains the principal material for use of RJ connectors in computers, networking devices and for other electronic products for the industries in the communications, automobiles, appliances, and industrial machinery equipment marketplaces. Because of phosphor bronze metals vulnerability to attack by aggressive chemical environments or even from simple atmospheric oxidation, metal coating is necessary to provide various degrees of protection. Xmultiple has developed a chemical coating sealant which is applied to the contact pins and to the metal shielding material if the RJ connector is of the shielded variety. The metal shielding of the RJ connectors is made of copper alloy and tin plating. The Xmultiple chemical coating sealant is applied in a hot-dipped process to evenly providing a tough chemical coating to protect the contact pins and shielding. In general, corrosive environments contain more than one active material, and the coating must resist penetration by a combination of oxidizers, solvents, or both. The Xmultiple sealant connectors are only a deterrent to the environment conditions and cannot guarantee protection from all these conditions over a long period of time. Xmultiple warrants testing must be done by each user to determine if our sealant will work in your specific conditions).