The BX2 pack is a multi piece unit, consisting of the main section, and then a secondary shoulder unit. The main uses a thin flexible plastic sheet for its frame body, with padded mesh back and hip covers, waist strap, and an attached nylon storage bag with two compartments. The secondary unit also uses the same thin plastic flex frame material, and attaches to the main pack with multiple large Velcro straps. It has padded shoulder straps, which attach to its upper frame with a free-floating system, allowing the straps to adjust, angulate and undulate as required. The lower strap connects to the main section’s trapeze, which extends around the bottom of the pack, helping to compress and pull up the load for better weight distribution and tighter center of gravity.
The pack comes in two sizes, regular (heights 155 – 175cm/5’1 – 5′ 9 ) and large (170 – 195cm/5’7 – 6’5), and each of those has an additional adjustment for four torso lengths, small, medium, large and x-large. The torso alteration is accomplished by detaching and reattaching the three Velcro points, which consist of the two back pads and the main center size adjuster. To change the length, you open the back mesh pads, and loosen the shoulder flex frame, and then back out the center strap. Choose the proper sizing for your torso using the pack’s instruction manual, although it will sometimes require some trial and error to get things worked out optimally. Starting from the back of the shoulder system frame, insert the center Velcro webbing up through a slot that is above the chosen lettered size (S, M, L, XL), and then insert the strap down into the next lower slot, covering over your size. Snug the center strap tightly, and push the Velcro down, and then roll the back pads over and push and snap them in place. The sternum strap is length and height adjustable so you can position as desired. Ergon refers to this entire system as the ‘Perfect Fit Backpack’.
The shoulder frame pokes out with A shaped ending in which the shoulder straps fit, and the straps are then attached through their webbing onto a set of D-rings, so the entire system is free floating, allowing for varying shoulder widths and sizes, and pack and body movement. The included rain cover upper straps get attached by sneaking them under the frame sheet and shoulder strap, and the bottom portion wraps underneath the pack with elastic edging.
The back and hip padding is quite soft and thick, and the mesh uses a nice open weave for maximum comfort, ventilation and wickability. The padding is rather tall (3/8-1/2 inch), and due to its separation, it creates a large and wide air channel, so the back and waist have great ventilation, keeping thing’s more comfortable and drier (no wet spots).