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Klein ET120 vs TopTes PT520A: Which Gas Leak Sniffer Deserves the Drawer?

The Klein ET120 and the TopTes PT520A are gooseneck combustible gas sniffers with the same documented 50 to 10,000 ppm methane range. The Klein has an 85 dB tone and a High/Low range switch; the TopTes has a 75 dB tone, a mute button, seven bars instead of five LEDs and a switchable auto power-off. Which one you want depends on where you use it.

By the Akermin Editorial Team · 5 min read

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If the sniffer will live in a noisy garage or a technician’s bag, buy the Klein ET120: its 85 dB tone is louder than the PT520A’s 75 dB, and its High and Low sensitivity ranges let you pinpoint a large leak that would peg a single-range display. If it will live in a kitchen drawer or an RV cabinet, buy the TopTes PT520A: it has a mute button, a switchable 10 minute auto power-off, a seven-bar display and a protective case, and it costs you nothing in documented sensitivity, because both tools state the same 50 to 10,000 ppm methane range. Neither shows a number, and neither replaces a fixed alarm. The rest of this comparison explains how we reach that split.

Sweeping a gas sniffer along a pipemove slowly, an inch or two from the pipe, pausing at every jointbars rise at the leakWarm up in clean air first. Reading peaks at the leaking joint and falls as you pass it.
Both sniffers work the same way: warm up in clean air, then sweep the probe tip slowly along each fitting and watch for the peak.

Two Sniffers Built for the Same Job

Both are handheld combustible gas leak locators with a flexible gooseneck, and both manufacturers document the same methane range. The Klein listing states approximately 50 to 10,000 ppm, split into a High setting of 50 to 1,000 ppm and a Low setting of 1,000 to 10,000 ppm. The TopTes listing states 50 to 10,000 ppm with a 0.5 second response and a recommended probe distance of 1 to 5 cm from the suspected source. Both are used the same way: power up in clean air, wait for the self-check, then move the tip slowly along every joint. Neither listing names its sensor technology, so treat any talk of a heated semiconductor element as background on the product class, not a specification for either unit. How that class of sensor works is covered in semiconductor gas sensors.

Side by Side

Item Klein ET120 TopTes PT520A
Documented range About 50 to 10,000 ppm (methane) 50 to 10,000 ppm (methane)
Sensitivity control High (50 to 1,000 ppm) and Low (1,000 to 10,000 ppm) Not stated as a switch; mute button instead
Response time Not stated 0.5 seconds
Visual indication Five red LEDs Seven colored bars
Audible alert 85 dB, intensifies with concentration 75 dB, increases with concentration; mute button
Gooseneck 18 inches, clips to the meter for storage 17 inches
Warm-up Automatic zero-point calibration at power-up; LEDs flash during self-calibration 30 seconds in clean air
Auto power-off Not stated After 10 minutes of inactivity, switchable via APO button
Power Not stated on the listing Three AAA batteries, included
In the box Detector Detector, three AAA batteries, protective case, user manual

Where the Klein ET120 Wins

Volume. An 85 dB tone is the difference between hearing the alert over a running furnace and not. In a basement mechanical room or a shop, the PT520A’s 75 dB is easy to miss when your head is inside a cabinet and the tool is at arm’s length.

The range switch. Once a leak lights every LED in High, switching to Low spreads 1,000 to 10,000 ppm across the same five LEDs, so the bar becomes useful again for finding the exact fitting. The PT520A has no equivalent control; its seven bars simply sit at the top when the leak is large. For anyone who wants to narrow a strong leak to one joint, that switch matters more than the two extra bars.

The extra inch and the clip. An 18-inch gooseneck that clips to the body for storage is a small ergonomic edge in a toolbox that gets thrown around.

Where the TopTes PT520A Wins

Mute. The escalating beep is how a sniffer tells you that you are getting closer, but during a long sweep of an RV’s propane system, or near a sleeping household, it becomes wearing. The PT520A lets you silence the tone and work by the bars alone. The ET120 lists no mute.

Auto power-off. The PT520A shuts down after 10 minutes of inactivity unless you disable it with the APO button, which saves the AAA cells when the tool gets left on in a drawer. The Klein listing does not state an auto-off.

Documented details. The TopTes listing states a 0.5 second response, a 30 second warm-up, a 1 to 5 cm probe distance and the battery type, and it ships with batteries and a case. The Klein listing is silent on response time, warm-up duration and battery type. That is not evidence the ET120 is worse; it is evidence that the PT520A buyer knows more about what they are getting.

Finer display. Seven bars resolve a rising concentration slightly better than five LEDs, which helps when two fittings a few inches apart both respond and you want to know which is stronger.

Who Should Buy Which

  • HVAC and plumbing technicians, garage and shop users: Klein ET120, for the louder alert and the High/Low switch.
  • Homeowners checking a range, dryer or water heater a few times a year: either; the PT520A’s case and included batteries make it the more complete purchase out of the box.
  • RV and boat owners: TopTes PT520A, for the mute and the auto power-off.
  • Anyone who wants a number on screen: neither. The TopTes PT210S displays a two-digit percent LEL reading on a 4-inch probe, and the reviews of the ET120, PT520A and PT210S go through each in detail.

What Neither Sniffer Does

Both top out at 10,000 ppm, which is one fifth of the lower explosive limit of methane, so neither can tell you a room is safe to enter; see what LEL means on a gas detector. Both are locators for checking fittings in air that does not already smell of gas. If a room smells strongly of gas, the sniffer stays put: leave, keep your hands off switches on the way out, and call the gas utility or 911 from outside. Both also respond to solvents, so a chirp near fresh paint or a can of cleaner is not proof of a leak until it repeats at the same fitting after airing the room out.

The Rest of the Field

Both tools are ranked against pocket and telescoping models in the handheld gas leak detector roundup, and home inspectors weighing a sniffer against a CO meter for their kit will find the ET120 in the gas detectors for home inspectors guide. The PT520A versus PT199 comparison covers the gooseneck-or-pocket question within the TopTes line.

Klein Tools ET120 Gas Leak Detector

Klein Tools ET120 Gas Leak Detector

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PT520A Natural Gas Detector, Gas Leak Detector with 17-Inch Gooseneck, Locating The Source Like Propane, Methane, and Butane for Home and RV (Includes Battery x3) - Orange

PT520A Natural Gas Detector, Gas Leak Detector with 17-Inch Gooseneck,

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TopTes PT210S Gas Leak Detector, Natural Gas Detector with 4-inch Probe, Propane Leak Detector Locating Combustible Gases Like Natural Gas, Methane for Home, Measures%LEL (Incl. Batteries) - Orange

TopTes PT210S Gas Leak Detector, Natural Gas Detector with 4-inch

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Products shown because their documented specifications fit this guide. Price and availability are on Amazon and can change.

Frequently Asked Questions

Are the ET120 and PT520A equally sensitive?

On paper, yes. Both manufacturers state a detection range of about 50 to 10,000 ppm based on methane, so neither has a documented sensitivity advantage. The differences are in how they present that reading and how loud they are about it.

Which one has the longer probe?

The Klein ET120 lists an 18-inch flexible gooseneck; the TopTes PT520A lists a 17-inch gooseneck. One inch is not a practical difference for reaching behind a range or into a water heater closet.

Does either sniffer show a ppm number?

No. The ET120 shows five red LEDs and the PT520A shows seven colored bars, both rising with concentration. If you want a number, the TopTes PT210S displays a two-digit percent LEL reading, at the cost of a short fixed probe.

Which is better for RV use?

The PT520A, mainly for the mute button and the included protective case. RV propane checks happen in cramped compartments near sleeping family members, and silencing the tone while watching the bars is a real convenience there.

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