The main RuneScape Wiki has an article on: Medium Mithril Helmet
The Old School RuneScape Wiki also has an article on Medium Mithril Helmet.

The Medium Mithril Helmet is a helmet which can be worn by players with at least level 20 defense. It requires at least level 53 smithing to make from one mithril bar, granting 50 smithing experience. It can also be bought from Peksa's Helmet Shop in Barbarian Village for 780 coins.

Bonuses

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