40oz Stainless Steel Tumbler vs Stainless King Tumbler: which is safer?
Stainless King Tumbler is our pick: better on PFAS and on the overall hazard picture.
Calpak
40oz Stainless Steel Tumbler
PFAS grade
A 95/100
Overall grade
B 83/100
Verdict
Buy
Hazard flags
⚑ 3
Material
Stainless steel, bare uncoated
Confidence
78%
PossibleNickel leaching (stainless steel alloy)
PossibleLid gasket and seal degradation
PossibleBacterial or mold growth in insulation gap
Our pick
Thermos
Stainless King Tumbler
PFAS grade
A 95/100
Overall grade
A 91/100
Verdict
Buy
Hazard flags
⚑ 1
Material
Stainless steel interior, plastic exterior lid
Confidence
78%
PossiblePlastic lid degradation and leaching
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 drinkware tumblers: see the full ranking