"A helmet made from ancient techniques and electricity-resistant material. It's made from something called "rubber," a material that can no longer be found."
The Rubber Helm is a helm found in Breath of the Wild. It has a base defense of 3 and provides a resistance to electric damage. It sports a black and yellow aesthetic, in a shape reminiscent of a fish. It is obtained by completing the Thunder Magnet side-quest at the Lakeside Stable, given by Cima.
The Rubber Set, which also includes the Rubber Armor and Rubber Tights, gives Link Shock Resistance. When all pieces have been enhanced at least twice, this will make Link invulnerable to lightening strikes.