OG Sack - Black Washable/Removable Liner - We understand that the inside of bags get dirty from clothes, food, and liquids. Therefore, we provided each OG Sack with a three pocket, removable liner that is washable. Multiple Strap Integration - Can wear it 3 different ways. - Messenger Style, Tote Style, Backpack Style One Bag One Tree - For every OG Sack that you purchase, one tree will be planted in the Atlantic Forest of Brazil.