Fitbit · Waterproof Smartphone Cases
Fitbit Sense Smartwatch
No coating described, and no PFAS statement from the brand.
The product information we reviewed describes aluminum, stainless steel, rubber, with no water-repellent coating named. Water resistance on products like this usually comes from the material and its seals rather than a surface treatment. The brand has published no PFAS statement for it.
We flunk more products than we pass. This one earned its grade. How we grade
Material
Aluminum, stainless steel, rubber
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
What’s concerning
Category baseline
The starting point for this type of product, before anything specific to this product is counted.
No PFAS disclosure
No public statement from the brand about PFAS in this product.
Rubber band skin contact and additives
Elastomer straps may contain plasticizers or accelerators that can leach with sweat and heat. No testing of the Sense band composition is publicly available; sensitivity varies by individual skin chemistry.
Bacterial and fungal growth on rubber and crevices
Wearable devices with rubber bands and metal-rubber interfaces are known to harbor microbes if not cleaned regularly, particularly in warm or damp conditions. This is a use and maintenance issue, not a manufacturing defect.
Aluminum oxidation and surface degradation
The aluminum case may develop white oxide or patina over years of wear, and micro-cracks in any protective anodize layer could allow trace aluminum or contaminant absorption. Long-term skin exposure risk is minimal but not zero.
Allergic reaction to stainless steel or nickel content
Stainless steel components can contain nickel (typically 8-12% in 300-series alloys). Individuals with nickel sensitivity may experience localized dermatitis; no specific nickel content declaration from Fitbit is available.
What’s reassuring
Base material not linked to PFAS
The main material recorded for this product is not one associated with PFAS.
Heavy metals
No published assay or third-party certification for lead, cadmium, or other heavy metals in the case or bands. Absence of evidence is not evidence of absence, but no incidents have been reported for this model.
Source, FDA ↗The full breakdown
What it's made of and why it matters
The Fitbit Sense case is primarily aluminum alloy with stainless steel components and rubber straps. Aluminum in direct contact with skin is generally well-tolerated, though anodized or painted finishes can degrade over time and release trace metals. The rubber band is the main soft-contact material; untreated or recycled rubber can leach additives, but typical elastomer bands meet consumer standards. No ceramic glaze, protective coating, or metal plating has been publicly disclosed on this device.
The brand's record and disclosure
Fitbit has not published specific material safety statements or heavy metal content testing for smartwatch components. The company does not appear to have faced major product recalls or documented contamination incidents related to the Sense body. Fitbit is owned by Google (since 2021) and provides standard consumer warranties but limited transparency on component sourcing or third-party safety testing.
How it compares in its category
Smartwatch construction is less regulated than cookware or food contact items, so baseline material safety varies widely. The Sense uses conventional industrial-grade materials found in most mid-to-premium smartwatches; rubber and aluminum are lower-risk than certain polymer finishes. Competitor devices (Apple Watch, Garmin) follow similar construction patterns, making the Sense materially typical rather than distinctive in safety terms.
If you buy it
Clean the rubber band regularly to prevent bacterial and fungal buildup, especially in warm or humid climates. Remove the watch during water exposure beyond its stated 50-meter rating (swimming poses lower concern; diving poses higher concern). Replace the band if cracking, discoloration, or persistent irritation develops; avoid prolonged contact with damaged elastomer. Store in a cool, dry place to slow rubber degradation and avoid prolonged heat exposure above 45 degrees Celsius.
What we don’t know
- Basis
- Model estimate, 35% confidence, not a lab result
- Lab test
- None on record for this exact product
- Brand statement
- Fitbit has made none
Formulations change between production runs, so check the current label. How we grade.
More waterproof smartphone cases grades
How we score, every product runs through the same public 0-100 rubric based on materials, coatings, brand disclosure, lab findings, and recalls. See the full methodology → Spotted a mistake? Report an error.