Tsuyoi Tsuyoi no Mi

Introduction
The Tsuyoi Tsuyoi no Mi, or Strong Strong fruit is a paramecia devil fruit that makes the user a Boron Nitride man. Bornon Nitride is a chemical compound made mof Boron and Nitrogen in equal measure. The Boron Nitride is a matterial that is toughter than diamon.

Weaknesses
The user suffers from standard Devil Fruit weaknesses

http://en.wikipedia.org/wiki/Boron_nitride