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The most careful load statement on the shelf: 15 amps resistive, for the new version

Kasa Smart HS103

A two-pack of UL-certified HS103 smart plugs rated 15 amps resistive, each with a side button.

Kasa Smart Wi-Fi plug HS103 two-pack in white

Kasa Smart HS103

A two-pack of UL-certified HS103 smart plugs rated 15 amps resistive, each with a side button.

Pack
2 plugs
Maximum load
15 A resistive at 120 V AC — stated for the new version
Certification
UL certified
Control
Button on the side of each plug, plus the Kasa app
Voice
Alexa and Google Assistant
Wi-Fi
2.4 GHz only
Automation
Timer and countdown schedules
Origin
Designed and developed in Silicon Valley
Matter
Not stated by the maker
Amazon reference
B07B8W2KHZ
EAN
0840460604925
  • A physical button on each plug, shared only with its own four-pack on this shelf
  • The only listing here that qualifies its load rating — 15 A resistive, at 120 V AC — rather than quoting a round figure
  • The load rating is footnoted as applying to the new version, so an older unit may differ

Best for: Two lamps or fans, where the manual button and the UL mark are the deciding factors

≈ $15
Check price on Amazon

Specifications

Pack
2 plugs
Maximum load
15 A resistive at 120 V AC — stated for the new version
Certification
UL certified
Control
Button on the side of each plug, plus the Kasa app
Voice
Alexa and Google Assistant
Wi-Fi
2.4 GHz only
Automation
Timer and countdown schedules
Origin
Designed and developed in Silicon Valley
Matter
Not stated by the maker
Amazon reference
B07B8W2KHZ
EAN
0840460604925

What the maker puts in writing

  • 2 plugs · 15 A resistive at 120 V AC, for the new version
  • UL certified
  • Button on the side of each plug
  • Alexa and Google Assistant · Kasa app
  • 2.4 GHz Wi-Fi required

The most careful load statement on the shelf

15 Amps Resistive @ 120VAC.

Resistive is the operative word. A heater, a lamp or a kettle is a resistive load; a compressor or a pump is not, and it draws several times its running current for a moment at startup.

Five plugs on this shelf publish 15 A without saying what kind. One publishes it with the qualification, and that one is this.

And the asterisk after it

The rating is footnoted as applying to the new version. That is honest and it is also a question: there is no way from this page to know which version arrives.

Availability

Read on the day this page was built: $15 at the American Amazon shop.

Read from Keepa on the day this page was last revised; stock and price both move without notice.

Prices quoted in this text were read on 2026-10-04. The live price is at the top of the page.

The questions that keep coming up

What does "15 Amps Resistive" mean?

That the rating applies to resistive loads — heaters, lamps, kettles — rather than to motors, which draw a surge at startup. It is the most precise load statement on this shelf; five other plugs publish a flat 15 A with no qualification.

Why does the footnote mention a new version?

The listing gives the rating as 15 amps resistive at 120 V AC and footnotes it, with asterisks, as applying to the new version. The implication is that an earlier HS103 was rated lower. If you are buying for a heater, that footnote is worth confirming with the seller.

Two-pack or four-pack?

Same plug, same price per socket on this shelf. The four-pack is the one to buy unless two is genuinely all you need.

More smart plugs & timers

  • Kasa Smart Wi-Fi plug HS103 in white with side button

    Kasa Smart HS103P4

    A four-pack of UL-certified 15-amp smart plugs with a physical button on each, controlled by the Kasa app.

    Pack
    4 plugs
    Rating
    15 A
    Certification
    UL certified
    Control
    Touch actuator on each plug, plus the Kasa app
    Voice
    Alexa, Echo and Google Home; no hub required
    Wi-Fi
    2.4 GHz only
    App support
    Android 5.0 or higher, iOS 10.0 or higher
    Automation
    Timer and countdown schedules
    Matter
    Not stated by the maker
    Amazon reference
    B07RCNB2L3
    EAN
    0840030702174
    • A physical button on every plug, so a lamp can be switched without a phone or a network
    • UL certified — the strictest named certification on this shelf — and 15 amps published
    • 2.4 GHz only, like six of the eight plugs on this shelf

    Best for: Four lamps or fans where a manual override matters as much as the app

    ≈ $34
    Check price on Amazon
  • SONOFF Matter smart plug S41s, white square body with status light

    SONOFF S41STPB

    A four-pack of Matter 15-amp plugs with surge and lightning protection in fire-resistant V0 casings.

    Pack
    4 plugs
    Rating
    15 A, 1,800 W
    Protocol
    Matter
    Ecosystems
    Alexa, Google Home, Apple HomeKit, SmartThings
    Protection
    Built-in surge and lightning protection
    Material
    Fire-resistant V0 PC
    Certification
    ETL
    Automation
    Timers and schedules
    Wi-Fi band
    Not stated by the maker
    Amazon reference
    B0FSZS357P
    EAN
    6920075743838
    • The only plug on this shelf with surge and lightning protection, and the only one that names a flame rating for its casing
    • Matter with HomeKit named, across four ecosystems, at seven and a half dollars a plug
    • Does not state which Wi-Fi band it uses, where six plugs on this shelf do

    Best for: A household on HomeKit, or anywhere the mains is unreliable enough that surge protection is worth having

    ≈ $30
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  • SwitchBot Plug Mini smart plug with power monitoring

    SwitchBot Plug Mini

    SwitchBot's Plug Mini adds app scheduling, voice control and live power monitoring to any 16A-rated appliance on this site, including the ones without their own app connectivity — most of the fans, heaters and evaporative coolers reviewed here. Confirmed with a live offer on Amazon.de; we found the same listing on Amazon.fr and Amazon.it but did not confirm live offers there at the time of checking.

    Rating
    16A, Type F (Schuko)
    Connectivity
    Wi-Fi, Matter-compatible; Alexa, Google Home, Apple Home, Home Assistant
    Monitoring
    Live power/energy consumption readout in the app
    EAN
    0810150544350
    • Confirmed with a live offer on Amazon.de at a genuinely low price
    • Power monitoring turns any plugged-in appliance into one you can track energy use for, useful alongside this site's running-cost guides
    • We found matching listings on Amazon.fr and Amazon.it but did not confirm live offers there at the time of checking

    Best for: Anyone who wants to schedule or track the power draw of a fan, heater, or humidifier that doesn't have its own app, without buying a new appliance to get that feature.

    Search Amazon for this model

Elsewhere in the spares drawer

  • LittleGood 6-inch analog wall thermometer and hygrometer with white ABS case

    LittleGood HMTMHY-WT

    A 5.9-inch analog dial reading −30 to +50 °C (122 °F) and 10 to 100 per cent humidity, with a calibration screw on the back.

    Type
    Analog — no batteries
    Dial
    5.9 in / 15 cm diameter, large black numerals
    Temperature
    −30 to +50 °C (122 °F) / −20 to +120 °F, accuracy ±2 °C (36 °F) / ±3.6 °F
    Humidity
    10 to 100%, accuracy ±5%
    Calibration
    Adjustment screw on the back for the temperature
    Scales
    Both Fahrenheit and Celsius, color-coded dial
    Mounting
    Supplied stand, or wall mounting hole
    Case
    White ABS
    Refresh rate
    Not applicable — analog
    Amazon reference
    B09P37W7CY
    EAN
    0613965381178
    • The only analog instrument on this shelf that publishes both tolerances and includes a calibration screw
    • A 5.9-inch dial with large numerals, readable across a room, which no digital display here matches for size
    • ±2 °C (36 °F) is the loosest temperature tolerance published on this shelf

    Best for: A wall in a garage, porch or workshop, read from across the room, with no battery to change

    ≈ $14
    Check price on Amazon
  • Reed 8706 digital psychrometer and thermo-hygrometer with dual-line LCD

    Reed 8706

    A digital psychrometer displaying humidity, temperature and dew point or wet bulb together, with Max/Min/Avg and data hold.

    Displays
    %RH, temperature and dew point or wet bulb, simultaneously
    Readings
    Max, Min and Average
    Data hold
    Yes
    External probe
    Optional 87P6, for contact and differential temperature
    Units
    User-selectable °F / °C
    Power
    Batteries; low-battery indicator and auto shut-off
    Stated uses
    Environmental studies, food distribution, HVAC/R installation, greenhouses, industrial spaces, saunas, humidors, museums, lab monitoring
    Accuracy
    Not stated by the maker
    Range
    Not stated by the maker
    Amazon reference
    B0C6BJ612L
    EAN
    0800837000057
    • Shows humidity, temperature and dew point or wet bulb on screen at the same time — the only instrument on this shelf that does
    • An optional external probe for contact and differential temperature, which no other device here offers
    • No accuracy and no measurement range published anywhere in the listing

    Best for: HVAC work, a humidor, a museum case or a greenhouse, where dew point matters and the reading has to be recorded by hand

    ≈ $125
    Check price on Amazon
  • TempPro TempAir digital hygrometer and indoor thermometer with wide LCD display

    TempPro TP53

    A digital hygrometer accurate to ±2 °F with all-time and 24-hour high and low records and a touch-activated backlight.

    Temperature accuracy
    ±2.0 °F (±1.1 °C)
    Humidity accuracy
    ±2 to 3% RH
    Refresh
    Every 10 seconds
    Records
    All-time and 24-hour high and low, stored and displayed
    Comfort indicator
    Yes
    Backlight
    Touch-activated, via a button below the display
    Mounting
    Holder, hanging hole and magnetic back
    Range
    Not stated by the maker
    Logging
    High and low only — no curve or export
    Amazon reference
    B079N98K93
    EAN
    6971604200285
    • The only device on this shelf that keeps high and low records — both 24-hour and all-time — without needing an app
    • Publishes both tolerances, with the humidity figure tighter than two cheaper devices here
    • A ten-second refresh, the slowest of the three published on this shelf

    Best for: A nursery, cellar or greenhouse where the overnight low matters more than the live reading

    ≈ $16
    Check price on Amazon

All smart plugs & timers