Think Tank Rotation 360 Backpack Beltpack Can Be Used Separately: The beltpack can also be used separately without the backpack. When you arrive at your travel destination, if you do not need the backpack you can just take the beltpack. A lightweight shoulder strap is included "Rail" for Modulus Components: On one side of the waistbelt is a "rail" that allows other Modulus accessories, such as the Lens Changers, Trim Changer, or Lens Drop In, to be attached. As with all Modulus components, you can allow it to "rotate or lock" Mesh Side Pockets, Built in Side Pocket: Each side of the beltpack has mesh pockets with a bungee/ toggle closure for fast access to smaller accessories. A built in side pocket is perfect for CF card wallets, 1.4x teleconverters and more 70-200 2.8 Lens "Rail" on the Beltpack: There is a "rail" on the side of the beltpack that allows for Modulus components to be attached. The Lens Changer 75 can be attached and will hold a 70-200mm f/2.8 or similar lens Front Pocket: The front pocket is for miscellaneous items and the raincover is located inside, as well