Perimeter 35 Backpack vs Dry Sack 3L w/Window: which is safer?

Osprey Dry Sack 3L w/Window is our pick: better on PFAS and on the overall hazard picture.

Granite Gear

Perimeter 35 Backpack

PFAS grade

F 20/100

Overall grade

F 0/100

Verdict

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Hazard flags

⚑ 3

Material

nylon with water-repellent coating finish, unknown type

Confidence

45%

Possiblewater-repellent coating finish composition (PFAS vs. fluorocarbon-free)

PossibleMicrofiber shedding from synthetic polymer

LikelyDegradation of coating over time

Why this grade

Our pick

Osprey

Dry Sack 3L w/Window

PFAS grade

F 20/100

Overall grade

F 8/100

Verdict

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Hazard flags

⚑ 3

Material

nylon fabric with water-repellent coating, window unclear

Confidence

45%

PossiblePFAS in water-repellent coating

PossibleMicroplastic shedding from coating degradation

PossibleWindow material identity and leaching

Why this grade

Both products run through the same public rubric: materials, coatings, brand disclosure, lab findings, and recalls, plus a beyond-PFAS hazard analysis. Grades are model-based estimates, not lab tests. How grades work →

More waterproof outdoor bags: see the full ranking