The TWL-1S is a heat stress meter designed to help protect your team. Rest easy with built-in risk flags that help your know when to work, rest or hydrate.


TWL-1S is designed for all kinds of worksites including mining and construction. All devices have been tested in rigid environment settings.


Our product is based on the scientific research and algorithm, which gives user built-in risk level flags and instruction for work, rest and hydration.


Free software allows users to download data on TWL and WBGT; air temperature, humidity, wind speed, globe and wet bulb temperature.


We ensure every devices with calibration providing accurate and reliable readings. The 3rd Party Certification is available upon request.

User-Friendly Dashboard

Meters were supposed to sense the targets and give readings. Scarlet intends to do more. TWL theory determines the threshold for safe, fair, and dangerous working environment. Colorful LCD backlight tells you the risk level based on the TWL value. Work-rest schedule and fluid intake are integrated into the display. A countdown timer shows the time remaining before a recommended rest.

Automatic Warning (TWL-1SR Model)

The working timer starts counting according to TWL value. When it expired, the device will notify the pager carriers remotely. It reminds you to take actions. 433 MHz technology is used to offer better penetration ability and 200 meter coverage in an open area is achieved. Please note that pager is available in TWL-1SR model.

Sensor Protection

Delicate temperature and humidity sensor are well protected by a replaceable polypropylene (PP) filter in a solid shield, exempted the sensors from dust damage and external strike. A silicone pad protects the mechanism of anemometer from dust.


loggerlogoTWL-1S can record data with configurable sampling rate from 10 minutes to 3 hours. PC side software automatically convert data into CSV format and helps download the data for further analysis using other analytical tools, and it also synchronizes the date and time of the device with PC.


globelogoTWL theory considers mean radiant temperature (MRT), the most important parameter on human energy balance. The smaller the surface area of the black bulb, the greater the effect of the air temperature and velocity is, thus causing inaccuracy. The 7.5 cm globe bulb is the optimal size based on our research.


cuplogoCup anemometer captures winds from any direction. You do not have to manually decide the wind direction before measuring the wind speed. Compared to the impeller, wind cup is not restricted to the direction of the wind. It considers all the horizontal components of winds that move the anemometer.