The main RuneScape Wiki has an article on: Mithril Plate Mail Legs
The Old School RuneScape Wiki also has an article on Mithril Plate Mail Legs.

Mithril Plate Mail Legs are plate mail legs that can be worn by players with level 20 defense, and made using 3 mithril bars at level 66 smithing.

They can be exchanged for a Mithril Plated Skirt from Thrander in south-eastern Varrock, and can be bought from Louie's Legs located in eastern Al Kharid.

Bonuses

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