The Bombproof Ring is a Magical Ring that Link can obtain in Oracle of Seasons and Oracle of Ages. Link can acquire the ring by planting a Gasha Seed and finding it within a Gasha Nut. He can also acquire it in a Seed Ring form by bumping into Maple. The ring can also be obtained through a Fortune Link at Vasu's jewelry store.
"No damage from your own Bombs"
When equipped, the Bombproof Ring makes Link immune to damage from his own Bombs. While it might not appear to be a very useful Magical Ring, it could be used during certain Boss or Mini-Boss battles where Bombs are used. Link can toss bombs a bit more carelessly, as he does not need to worry about taking damage himself.