eufy Smart Sock S320

What it is

A wearable wellness sock for babies 0–18 months / up to 30 lbs: a photoplethysmography (PPG) sensor (42 × 38 × 13.5 mm, 8 g) sits on a soft, washable fabric wrap — three sizes in the box, wearable on either foot — and reads heart rate, blood oxygen (SpO2) and movement, which the eufy Baby app turns into sleep state, sleep time and daily sleep reports. The sensor talks to the base over Bluetooth Low Energy; the base reaches your phone over 2.4 GHz Wi-Fi only and doubles as the magnetic charging dock and the glanceable status light (green = fine; red light plus sound = check the baby). Battery is up to 24 hours per charge, about 2 hours to recharge. Alerts fire when vitals change or the sock detaches, and are customizable. There is no camera and no audio in the S320 — this is the sock-only kit (model T8352), not the S340 bundle ($279.99–$329.99), which adds a 2K camera around the same sock. Warranty: 12 months (the S320 user guide).

Claims vs. reality

“The same thing as Owlet, only cheaper” — false on the point that matters. Same shape, yes: a foot-worn sensor reporting heart rate, oxygen and sleep. But eufy states in its own fine print that the Smart Sock “is not a medical device” and “cannot be used to diagnose, treat, cure, or prevent any disease or condition, including… sudden infant death syndrome (SIDS).” The Owlet Dream Sock (check #12) holds an FDA De Novo clearance as an over-the-counter pulse oximeter with a published ±3% clinical accuracy citation. eufy publishes no accuracy figure at all — its claim is a mechanism (“a Fresnel lens” refracting infrared light), not a measurement. Neither sock prevents SIDS, and safe sleep does the real work for both — but only one has had its numbers vetted by a regulator.

“No monthly fee” — true, and the cleanest win here. eufy’s own FAQ: sleep data, history and reports are accessible “at zero cost,” no subscription or contract. The Owlet’s live readings are free too, but its trend reports sit behind Owlet360 at $9.99/mo. Budget the eufy as its sticker price, full stop.

“Real-time” alerts — the tested seams. BabyGearLab tested the S340 — the same sock, sensor and base with a camera added — and scored it below average for expected reliability: reports of inaccurate readings, and readings and alerts “when the sock is not being used” — in their own testing, the sock sent blood-oxygen and heart-rate notifications while sitting on a desk. Push notifications for out-of-range vitals are not persistent and repeat only about every ten minutes, and the base alarm they measured topped out at 66 dBa and can be snoozed without checking the baby. eufy’s own support file adds that sleep data is “slightly delayed” while the baby sleeps. As trends, the numbers are useful; as an alarm, this is weaker than the marketing tense claims.

Battery and comfort — the claim holds, with an asterisk. The 24-hour battery is corroborated by eufy support and owners, and drop-on magnetic charging makes the daily top-up easy. But BabyGearLab notes the sensor is larger than rivals’ and collects owner reports of skin irritation where it sits — and eufy’s own listing FAQ acknowledges red marks, imprints and even blisters from prolonged wear in heat or humidity or from kick friction. Correct size, clean dry feet and skin checks are operating requirements, not fine print.

The finding no listing page mentions: eufy says it discontinued the sock. A post on eufy’s own blog (Jun 5, 2026) states the Smart Sock “has been discontinued, and eufy no longer sells it new,” as the brand pivots to camera monitors that don’t track vitals at all. The same post promises existing socks keep working in the app, with support and warranty continuing and replacement socks available while stock lasts. Flagged contradiction: eufy’s product page still offered the S320 at $169.99 when this check ran, and Amazon still stocked it — a wind-down, not a switch-off. Buy knowing the app and accessories now run on a discontinued line’s clock.

Safety & recalls

Real reviews — what owners say

Owners like the product they got; testers question the readings it gives. Amazon’s record for this listing aggregates to about 4.3/5 across 899 reviews (pricehistory.app, Oct 2026), independently matched by ExpertBeacon’s record (4.3 across 845). eufy’s own store pool is rosier (4.79 across 152, brand-hosted); Best Buy’s is tiny (4.7 across 15, syndicated from anker.com and largely promotion-collected). The praise repeats in one voice: peace of mind and sleeping better, heart rate and oxygen together in one app, easy setup and an easy on/off sock, no subscription ever, and Owlet-shaped reassurance at roughly half the street price. The complaint spine: reading trust — vitals that are slow to appear or hard to believe (the pattern BabyGearLab’s below-average reliability score documents at platform level); connectivity — dropouts and “glitchy” reports, on a 2.4 GHz-only Wi-Fi link plus a Bluetooth sock-to-base link whose range depends on your walls; fit and skin — digging in on skinny ankles, red marks in heat; and the 24-hour battery ceiling — a forgotten charge is a blind night. Notably absent: any dead-unit pattern or a paywall ambush — the no-fee promise holds in the owner file.

Price & FSA/HSA

$139.99 at Amazon is the verified anchor for this listing (tracked Oct 21, 2026; the tracked range runs $115.33–$319.99, oscillating between $118.99 and $169.99 through 2025–26 — never pay above $169.99, and $118.99–$139.99 is the recurring sale band). eufy.com lists the same kit at $169.99 (its table still shows the $199.99 list) — Amazon is the cheaper channel, and the discontinuation wind-down argues for buying where returns are easiest. No running costs: no subscription, three sock sizes in the box; the tail costs are replacement wraps (brand-priced, while stock lasts) and battery wear past the 12-month warranty. The framing comparison: the Owlet Dream Sock (check #12) is $299.99 list with FDA clearance and an optional $99.99/yr trend tier; the S340 camera bundle at $279.99–$329.99 buys this same sock at Owlet money with none of the clearance — it is not the shortcut it looks like.

FSA/HSA: flagged eligible — the flag appears in this listing’s Amazon feature set and on eufy’s own product page. No FSA Store / HSA Store listing was found in this check, so verify against your own plan before checkout and keep the receipt — doubly so for a product whose maker states it is not a medical device.

The verdict

WORTH IT IF… you want what this product actually is: a comfortable, fee-free wellness sock whose sleep reports and heart-rate/oxygen trends help you understand your baby’s nights, bought at the $118.99–$139.99 sale band with an 18-month window all you need. Then the file supports it: three sizes in the box, 24-hour battery with drop-on charging, a consistent ~4.3/5 owner file, low measured EMF, no recall, and honest pricing with no subscription tail. The conditions: you accept — in eufy’s own words — that it is not a medical device, with no FDA clearance and no published accuracy figure; you accept the tested alert limits (phantom readings, ten-minute push cadence, a quiet base) and keep safe sleep as the actual safety system; you run the fit and skin discipline; and you buy it as a discontinued line, eyes open, from a channel with easy returns. Not worth it if a clinician has asked you to watch your baby’s oxygen, or the numbers are the point — check #12’s cleared Owlet is that product, and this is not a substitute for it at any discount — or if alert reliability is the whole purchase, or you were about to pay S340 money for the same sock plus a camera.