The Sak’s Silverlake Canvas Convertible Satchel, $99, goes from hobo-bag to satchel when you change the strap.

Not only do you have two different styles, but if you load up your bag more than you expected you can switch to the more comfortable shoulder strap on the go.

The Sak and HarperCollins are ready to give away the bag and help you load it up too – with three new summer books! Just email bookinabag@harpercollins.com with your full name and email address in the month of May.

Then, throughout the summer you can enter to win a different The Sak bag and book each month.