Here are couple of items you should always have to hand or in your gig bag to make notes in your JustinGuitar Books or editing your charts.

The 4 Colour Pen contains Red, Green, Blue and Black. Great for highlighting certain passages. Justin is a keen user of the multicolour pen. 

The Mechanical pencil has a 7mm led and  has an eraser on the topis very useful so you can rub out your notes so you damage your very precious JustinGuitar Books.