Read what your
walls are
telling you.
Check walls, pipes and plugs with your phone. Find the leak, look inside the wall, prove it’s wet — before it turns into a repair bill.
The leak shows up cold.
The fault shows up hot.
Water evaporating behind plaster cools the wall. A loose connection heats the plug. Your eyes see a clean wall and a plug — Spark sees the wet patch and the overheating plug in a second. Drag the line.
- Plug it into your phoneUSB-C port only — it runs off the phone, no battery to charge.
- Open the free app“THG Start” for iPhone and Android. Hottest and coldest points are marked for you.
- Follow the colorPurple is cold, yellow is hot. Snap a photo to send to your plumber or landlord.
Look inside the wall
without opening it.
Drill one small hole — or use a gap you already have — and slide the camera in. A thumb wheel bends the tip so you can look around corners. The LED lights up only what the tip points at — turn it up to find the leaking joint.
- Clip your phone to the handlePlug in the cable — the picture appears in the app.
- Slide it inThrough a small hole, a drain, an air vent or an engine bay.
- Turn the steering wheelThe tip bends both ways and lights up what it sees.
The paint looks fine.
The number doesn’t.
Mold starts long before you can see it. Damp reads moisture 5–40 mm under the surface of plaster, cement and wood — no pins, no holes. Slide it across the wall and watch the number climb.
- Zero it in the airPress ZERO once — it calibrates itself in a second.
- Touch the ball to the wallThe reading appears on its color screen. No phone needed.
- Map the patchMove until the number drops — that’s the edge of the leak.
Start with what’s wrong.
We’ll tell you which tool.
Pick a tool to see the jobs it’s good for. Each job shows which tool to use first.
Leak behind the shower
Find the cold patch, prove it’s water, then look at the joint — before anyone lifts a tile.
Mold behind the dresser
Check the wall before it turns black. Cold corners and wet readings mean poor airflow or a leak.
Hot electrical panel or outlet
Loose connections run hot long before they fail. Spot them safely from a distance — then call an electrician.
Blocked drain or pipe
See if it’s hair, roots or a broken pipe before you pay for a plumber’s camera.
AC not cooling
Check vents, ducts and the mini-split. Uneven color shows blocked or leaking ducts.
Drafts and missing insulation
See exactly where winter heat escapes — around windows, doors and in the ceiling.
Before you buy or rent
A 15-minute walk-through with all three tools. Not a replacement for a licensed inspection — a way to know what to ask.
Inside an engine or appliance
Find the dropped bolt, check a cylinder, look behind the dishwasher without pulling it out.
Ceiling stain after rain
Trace where the water travels from the roof, and check if the plaster is still wet.
Five tools. Tap one to see it from every side.
Free tracked shipping, honest delivery dates, 30-day returns.
Spark
- Sensor96×96 · 25 Hz
- Range−4 to 752 °F (−20 to 400 °C)
- Works withiPhone 15 – 18 · Android 12+
Spark Pro
- Sensor256×192 · 25 Hz
- Range−4 to 662 °F (−20 to 350 °C)
- Works withiPhone 15 – 18 · Android 12+
Reach 360
- Camera6.2 mm · 2 MP · 8 LEDs
- Tipbends 180° each way
- Works withUSB-C phones
Reach Duo
- Camerafront + side · 1080p
- Cable1 m semi-rigid · IP67
- Works withLightning and USB-C iPhones · Android · adapters in box
Whole Home Kit
- Find, confirm, lookall three steps
- Separately$482
Pick your phone. See what plugs straight in.
We only mark a phone as compatible when we can stand behind it. iPhone 15 and newer and recent Android phones have USB-C; older iPhones have a Lightning port.
Thermal cameras work with every iPhone 15, 16, 17 and 18 model. Android phones need Android 12 or newer.
Before you buy
Doesn’t my phone already do this?
No. Phone cameras see light, not heat — thermal needs its own sensor and a germanium lens. “Thermal” apps only add a color filter. The Pixel Pro’s temperature sensor reads one spot, not a picture.
Do I need a special app?
Yes, a free app from the App Store or Google Play. The right one for your tool is named on its product page and in the manual in the box.
How long does delivery take?
Usually 7–15 days from your order, with tracking. Checkout shows the delivery estimate for your address — no “2-day” promises.
What if it doesn’t fit my phone?
Use the phone picker above before you order. If a tool doesn’t work with a phone we list as compatible, we refund you in full, including return shipping.
Where does it ship from? Are there import fees?
From our supplier’s warehouse in China, with free tracked shipping. US import duties or carrier fees may be collected on delivery; they aren’t included in our prices.