Stanley IceFlow Flip Straw Tumbler vs Cold Tumbler: which is safer?
Ember Cold Tumbler is our pick: better on PFAS and on the overall hazard picture.
Cuppy
Stanley IceFlow Flip Straw Tumbler
PFAS grade
B 85/100
Overall grade
C 73/100
Verdict
Buy
Hazard flags
⚑ 3
Material
stainless steel body, plastic lid/straw
Confidence
72%
PossiblePlastic lid and straw degradation
PossibleMicroplastics from straw wear
PossibleLid seal failure and bacterial growth
Our pick
Ember
Cold Tumbler
PFAS grade
A 100/100
Overall grade
A 92/100
Verdict
Buy
Hazard flags
⚑ 2
Material
stainless steel with silicone seal
Confidence
72%
PossibleSilicone seal degradation and microbial growth
PossibleCoatings or adhesives on printed logos
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 insulated travel drinkware: see the full ranking