The BACKPACK HARNESS KIT is compatible with the X-PAK EVO or X-PAK EVO v2 / Apex Liner Pro. This will convert your X-PAK EVO from a sling into a backpack / Apex Liner Pro 2+1 Way Shoulder Bag from a briefcase to a backpack. The front chest compartment is useful to store cards, earphones/earbuds and other small EDC items for quick and easy access. Also, the ANNEX LAPTOP CASE (sold separately) can work together with the BACKPACK HARNESS to carry up to a MacBook Pro 16" laptop (X-PAK EVO). To check to see if you have the newest X-PAK EVO or X-PAK EVO v2, take a look at the upper hypalon webbings on both right left sides of the bag. If you see a hole on the webbing, then your X-PAK is compatible with the BACKPACK HARNESS. Key Features: x1 zippered chest compartment (5 x 4" / 130 x 110mm) Reflective material used on front chest compartment Removable sternum strap w/ built-in whistle Removable waist strap Padded top grab handle