[Ricklin]

Any good Chandlery (ships store) marine supply will have that. It is very very good protection, I don't know what all is in it, I would not use it on wood.

A salt water boat is the worst environment extant. Commercial fish boats use that wrap on hydraulic fittings. They are hardened steel and rust like mad. The wrap seals them up tight, they thus can be taken apart if need be months or years down the road. They also keep the fitting from just rusting away and failing.
Good stuff. Prolly not for guns.