The BACKPACK HARNESS KIT is compatible with the X-PAK EVO. This will convert your X-PAK EVO from a sling into a backpack. The front chest compartment is useful to store cards, earphones/earbuds and other small EDC items for quick and easy access. Also includes a waist strap for more stability.
Also, the ANNEX LAPTOP CASE (sold separately) can work together with the BACKPACK HARNESS to carry up to a MacBook Pro 16" laptop.
To check to see if you have the newest X-PAK EVO, 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. See photo below.