Mithril bar certificate

A Mithril bar certificate is a certificate that is obtained by exchanging five mithril bars with Miles at Draynor Village market. Mithril bar certificates are stackable and each one can be exchanged back for five mithril bars by talking to Miles.

Because mithril bars are not stackable and you can only trade twelve items per trade screen, they are often exchanged for certificates so that they can be traded easier and faster.