Think Tank Essentials Convertible Rolling BackpackThink Tank Essentials Convertible Rolling Backpack The Essentials Convertible rolling backpack goes where other rollers cant. Roll smoothly through the airport then deploy the backpack straps to carry over rough terrain. Sized to meet most airline carry on requirements*, the Essentials fits two DSLR or Mirrorless bodies, a mounted 70200mm, multiple lenses, and a 16 inch laptop. And because its from Think Tank, the bag will roll long into the future.