MacPac sizing is hard to understand. For example, they say the back length for their largest size is 15 to 19 in, and the height range is 6 ft 1.5 in to 6 ft 6.5 in. Who would be that tall and have a torso length that short? I don't know which measurement to go by. Any clues, especially for size 3?

Tech Specs:

Material:

Titan Grid 

Volume:

[2] 2085cu in (34L); [3] 2198cu in (36L) 

Suspension:

Helium load system, HDPE frame sheet 

Waist-belt:

Yes 

Hydration Compatible:

Yes 

Rain Cover:

No 

Access Types:

Top 

External Pockets:

1 Lid, 1 front, 2 side 

Snowboard Carry:

No 

Ski Carry:

No 

Gear Loops:

None 

Ice Axe Loops:

None 

Shovel Pocket:

No 

Weight:

[2] 2lb 6oz (1150g); [3] 2lb 10oz (1200g) 

Recommended Use:

Lightweight backpacking 

Manufacturer Warranty:

1 Year 

Country of Origin:

United States