As for weather reading features, they will be the same. You won't get a 'better' temperature reading, wind reading, etc, or even more readings than available on the 4400/4600... still the same quality USA-made meter backed by a 5-year warranty. That being said there are some pretty outstanding updates.

• Flag warnings via loud buzzer & LED beacon!
• Bluetooth LINK works with PC/Mac via Dongle
• Bluetooth LINK to Smartphones / Mobiel / Android / IOS
• Takes 1 AA battery (instead of 2 AAA)
• The battery door is in the back, sealed away from the motherboard, should your battery leak as was common with all the 4000 series. All 5000 battery doors are the same and interchangeable.
• Slightly larger and improved higher contrast/resolution screen for any lighting (even sunlight) and easy on your eyes.
• Intuitive user-interface screen navigation
• Multiple Languages (English, French, German, Spanish)
• Scratch and breakage-resistant window
• All meters include both options of Red (NV - Night Vision) & White backlights.
• Slightly bigger, more robust, though not really noticeable difference.
• Roughly 10,000 data points. 4000 series all had under 5000 data points.

The Kestrel 5400 is revolutionary in size, cost, and capability for those in need of measuring Heat Stress. Available with or without LiNK (Bluetooth) and/or a compass.

Along with having a Wet Bulb Global Temperature reading, the Kestrel 5400 displays thermal work limit (-TWL-), another recognized composite heat stress prediction tool. For both WBGT and TWL, the Kestrel 5400 provides on-screen alarms when conditions enter the caution and danger zones, providing clear and immediate guidance that heat illness prevention steps must be taken. Clothing levels can also be customized, making the Kestrel 5400 particularly useful in activities requiring heavy protective gear which worsens heat stress. The Kestrel 5400 also displays natural wet bulb temperature and black globe temperature.

How Does the Kestrel 5400 Work?

The Kestrel 5400 uses a 1-inch black globe to gather information about the environment, which isn't possible with current Kestrels. As is true with the original Wet Bulb Globe Temperature apparatus, a temperature sensor is installed inside the globe that will measure the temperature inside. The temperature inside the globe is a function of the ambient air temperature, solar insolation and wind speed.

As one can imagine, a sunny day will make the globe hotter because it's painted black, and colder ambient temperatures will have a tendency to cool off the globe. Lastly, the wind will cause the globe to get closer to the ambient air temperature because it will carry heat away from the globe when the air is cooler, or increase heat transfer to the globe if the air is warmer than the globe.

The Kestrel must sit out for a period of time to allow the globe to adjust to true atmospheric conditions; we recommend a minimum of 7-10 minutes. The globe temperature is then taken into account along with other measurements, such as ambient temperature, humidity and pressure, to calculate more meaningful measurements, such as Wet Bulb Globe Temperature and Thermal Work Limit.

Indoor Use

Reading the WBGT is important even in indoor settings where heat stress is a concern. The Kestrel has an 'indoor' setting on the WBGT setting which basically turns off the function of taking into account the direct solar radiation from the sun. It's important to place the Kestrel in a representative area of the conditions that the workers face. Remember, wind plays a factor in WBGT, so a vane mount can be used indoors as well.

In the case of a ceiling fan, if the Kestrel doesn-TMt pick up the ceiling fan, then you are essentially getting the -worst-case- WBGT readings which is not actually a bad thing. If the airflow is pretty strong from the fan and you want to have that factored in, you could mount the Kestrel sideways (vs vertical) so the impeller picks up the wind more realistically. You can use the Clamp to achieve this.

- Wet Bulb Globe Temperature ("WBGT"). Thermal Work Limit ("TWL")

-This version is without LiNK (Bluetooth)

- Waterless! Natural Wet Bulb Temperature accurately calculated from onboard digital sensors with no tedious setup or maintenance.
- The large, hi-res, hi-contrast, graphic display is perfectly readable in the brightest sunlight and is backlit for use in low-light conditions.
- Globe Temperature. Naturally Aspirated Wet Bulb Temperature.
- Wind Speed (Current, Average, & Maximum)
- Altitude. Pressure trend. Barometric pressure.
- Relative humidity in %.Heat stress index.Dewpoint
- Wet-bulb temperature.Density altitude.Wind chill.
- Air, water, and snow temperature -F or -C.Waterproof.Time and date.
- Easy-to-read backlit display.Data Logger (automatic and manual)
- Customizable data storage - 2900 data points
- Humidity sensors can be calibrated in the field with our Relative Humidity Calibration Kit.
- Customize screens to display user-selected measurements
- Graph and recall trends. User-replaceable impeller
- Data charting. Upload to a computer (with optional interface)
- Meets MIL-STD-810F 516.5 Procedure IV Transit Shock test - 20 drops from 5 ft. IP-67 sealed to exclude dust and water at 3 ft. submersion
- Five languages (English, French, Spanish, German, and Italian)
- Made in the USA