For assessing indoor air quality: use the probe (with the compatible measuring instrument) to measure CO₂ concentration, humidity and air temperature. The readings are transmitted directly to your measuring instrument via Bluetooth, making your measurements particularly convenient.

For assessing indoor air quality: use the probe (with the compatible measuring instrument) to measure CO₂ concentration, humidity and air temperature.

More applications, less equipment: if you already own one of our probes with a universal handle, you can easily expand your portfolio of probes with the CO₂ probe head.

<div style="background-color:#dae4ea; border: 1px solid #648798; padding: 10px;"><b>Product no longer available. Have you checked out its successor?<br/>Why not enjoy the benefits that it has to offer:<br/> <a href="…/p/0632-1552">>> To the product (fixed cable)</a><br/> <a href="…/p/0632-1551">>> To the product (wireless, with Bluetooth)</a><br/>Please note that the successor products are only compatible with testo 400 or testo 440.</b></div>

Use the testo 420 differential pressure measuring instrument to carry out simple, efficient tests on filters. You can also use the measuring instrument in conjunction with a Pitot tube to measure flow velocity and volume flow really easily in ventilation ducts.

<div style="background-color:#dae4ea; border: 1px solid #648798; padding: 10px;"><b>Product no longer available. Have you checked out its successor?<br/>Why not enjoy the benefits that it has to offer:<a href="https://www.testo.com/400">>> To the product</a></b></div>

<div style="background-color:#dae4ea; border: 1px solid #648798; padding: 10px;"><b>Product no longer available. Have you checked out its successor?<br/>Why not enjoy the benefits that it has to offer: <a href="…/p/0560-4402">>> To the product</a></b></div>

Kit for evaluating the indoor air quality. The testo 440 air velocity and IAQ measuring instrument and the CO<sub>2</sub> probe with Bluetooth<sup>&reg;</sup> including temperature and humidity sensor are all safely stowed away in the case. So you can get down to work straight away!

Use this practical Indoor Comfort ComboKit to handle all relevant measurements in order to evaluate the indoor air quality in indoor areas and to determine the draught risk and degree of turbulence in workplaces. The testo 440 air velocity and IAQ measuring instrument, the CO<sub>2</sub> probe with Bluetooth<sup>&reg;</sup> including temperature and humidity sensor and the turbulence probe are all safely stowed away in the case. So you can get down to work straight away!

Precise, reliable measurement of all air velocity and IAQ parameters with just one measuring instrument: the multifunction measuring instrument features an integrated differential pressure sensor and intuitive operation with clearly structured measurement menus. Adjusting air conditioning and ventilation systems, monitoring air quality or carrying out comfort level measurements &ndash; thanks to versatile options for combining with high-quality, digital probes, you are ideally equipped to carry out your measuring task (please order probes separately).

Carry out measurements without any annoying cables: use the kit to handle all relevant measurements in ventilation ducts and at air/ceiling outlets. You will receive the testo 440 dP air velocity and IAQ measuring instrument including differential pressure sensor and the 100 mm vane probe head and hot wire probe head (Ø 9 mm) for attachment to the universal Bluetooth<sup>&reg;</sup> handle supplied.  To make measurements more convenient, both probe heads can be combined with the telescope included in the kit. The equipment can be transported safely and conveniently in the robust case.

Carry out measurements without any annoying cables: use the kit to handle all relevant measurements in ventilation ducts and at air/ceiling outlets. You will receive the testo 440 dP air velocity and IAQ measuring instrument including differential pressure sensor, two vane probe heads (Ø 100 mm and Ø 16 mm) and a humidity/temperature probe head – all three can be attached to the universal Bluetooth<sup>&reg;</sup> handle supplied. To make measurements more convenient, both vane probe heads can be combined with the telescope included in the kit. The equipment can be transported safely and conveniently in the robust case.

<div style="background-color:#dae4ea; border: 1px solid #648798; padding: 10px;"><b>Product no longer available. Have you checked out its successor?<br/>Why not enjoy the benefits that it has to offer: <a href="…/p/0560-0400-01">>> To the product</a></b></div>

The high-precision testo 521-1 differential pressure measuring instrument is ideal for accurate differential pressure measurements in air conditioning and ventilation technology, for instance for pressure drop on filters, checking fans and extractors or for Pitot tube measurements.

<div style="background-color:#dae4ea; border: 1px solid #648798; padding: 10px;"><b>Product no longer available. Are you familiar with the alternative?<br/>Why not enjoy the benefits that it has to offer:<br/> <a href="…/p/0560-5210">>> To the product</a><br/>

Extremely precise, rugged and practical: the testo 552 digital vacuum gauge. Ideal for evacuating refrigerant systems or heat pumps.

The testo 400 is the universal measuring instrument for all IAQ professionals. Measure, analyze and document all IAQ and comfort level parameters using just one instrument – simply, conveniently and in compliance with the standards. High-quality measuring technology, intuitive measurement assistants, versatile documentation options and a comprehensive selection of IAQ probes make the testo 400 the perfect partner for your day-to-day work.

Ideal kit for IAQ professionals, with a focus on indoor air quality and comfort level. You will receive the testo 400 universal IAQ measuring instrument with intuitive measurement menus, one CO₂ probe (with Bluetooth<sup>&reg;</sup> handle), one turbulence probe and one globe thermometer Ø 150 mm (both with fixed cable). Use the measuring tripod to ensure standard-compliant positioning of the probes. In combination with the IAQ data logger, which is available to order separately, long-term measurements up to 2 weeks can be recorded, even without the IAQ measuring instrument.

Ideal kit for IAQ professionals, with a focus on indoor air quality and comfort 
level. <br/><br/>You will receive the testo 400 universal IAQ measuring instrument with intuitive measurement menus, one CO<sub>2</sub> probe (wired), one turbulence probe and one globe thermometer Ø 150 mm (both with fixed cable). Use the measuring tripod to ensure standard-compliant positioning of the probes. In combination with the IAQ data logger, long-term measurements up to 2 weeks can be recorded, even without the IAQ measuring instrument.

Ideal kit for IAQ professionals, with a focus on air flow measurement. You will receive the testo 400 universal IAQ measuring instrument with intuitive measurement menus, one vane probe head (Ø 16 mm), one vane probe head (Ø 100 mm) and one high-precision humidity/temperature probe head – all three can be attached to the Bluetooth<sup>&reg;</sup> handle supplied. For measurements at ceiling outlets, simply combine the 100 mm vane probe with the telescope (can be extended up to 1.0 m) and the 90° angle.

Ideal kit for IAQ professionals, with a focus on air flow measurement. You will receive the testo 400 universal IAQ measuring instrument with intuitive measurement menus, one hot wire probe head (including temperature and humidity sensor), one vane probe head (Ø 100 mm) and one high-precision humidity/temperature probe head – all three can be attached to the Bluetooth<sup>&reg;</sup> handle supplied. For measurements at ceiling outlets, simply combine the 100 mm vane probe with the telescope (can be extended up to 1.0 m) and the 90° angle.

This ISO calibration certificate certifies that your measuring instrument or probe is calibrated. Calibration is carried out according to the ISO standard.

Product-/housing material	paper
Product colour	white

ISO pressure calibration certificate - with 5 measuring points

ISO pressure calibration certificate - with 5 measuring points

General technical data