From the product description, check product page for current description, price and availability:

Best-in-Class Airflow Technology: 46 CFM
This is why billows is able to stabilize and control temperature over your entire cook more efficiently than any competitor.

Controller Compatibility: Works with any ThermoWorks controller
Control your cook more efficiently with Billows and ThermaQ 2, SmokeX, or Signals.

Made to Fit Most Smokers
Easy to fit into any smoker’s BBQ fan opening.
(Optional mounting kits are available.)

Cook perfect, succulent BBQ meats over the course of many hours without having to worry about flareups, burn-outs, vent adjustments, or tending the coals. Confidently control your BBQ with ThermoWorks quality precision.

Billows now comes with Open Lid Detection, Billows returns the smoker to your set temp much quicker.

Maintains constant temperature control (±10°F/6°C typical) over entire cook
Fastest initial speed-to-temperature
Lowest overshoot, stabilizes faster
Control stability exceeds other units
One integrated system to monitor and control smoker and meat temps
Cool-touch industrial-molded weatherproof composite
Uses replaceable USB-C connector cables
True charcoal flavor without the hassle of fire tending
Engineered in Utah by ThermoWorks
When connected to a ThermoWorks compatible controller (required), the Billows fan quickly gets your smoker up to the target cooking temperature and keeps it there. The powerful 46 CFM fan maintains precise temperature control, whether you’re cooking in a stick-burner, ceramic, barrel, or drum cooker. An optional expansion connection kit is available to pair two Billows with the same controller for large smokers or cookers, but you’re not likely to need it, as powerful as Billows is. Up your game today with Billows.

Optional Billows Mounting Kits (sold separately) may be used to attach Billows to certain types of smokers. See the Question and Answers section for more details.

From the product description, check product page for current description, price and availability:

• Wi-Fi and Bluetooth built in for seamless connection and easy setup
• 4 channels, uses Pro-Series commercial-grade probes
• Works with ThermoWorks BBQ app and standalone
• Splash-proof sealed design for outdoor use, rated to IP66
• Stays in place with sturdy base and strong magnets on back
• Backlit dashboard-style display to track temps, alarms, Min/Max
• Rechargeable battery with included power adapter
• Designed in Utah by ThermoWorks

Designed for competition BBQ teams, commercial smokehouses, professional chefs, and those who want to cook like them, Signals with built-in Wi-Fi and Bluetooth boasts 4 channels of continuous temperature monitoring with all the powerful features and convenience you’ve come to expect from ThermoWorks.

Finally, a 4-channel alarm thermometer that works with your smart device AND as a stand-alone unit with physical buttons (so you don’t have to soil your smartphone). Signals comes with both Bluetooth™ and Wi-Fi onboard, seamlessly switching between the two, so you get a continuous signal and real-time alerts whether you’re in a field or across town. Setup is quick and easy without ever needing to read the instruction manual. Signals stands apart from the competition, from its huge, backlit dashboard display and sturdy, self-standing weather-resistant case to its programmable channel names and new high temperature silicone color bands so you know at a glance which channel goes with which probe. Signals uses commercial-grade Pro-Series temperature probes exclusive to ThermoWorks to deliver better accuracy, faster response, wider temperature ranges and longer useful life. Cook more at once and worry less about the results with Signals.

Signals is designed to track temperatures over an extended period of time with moderate-heat cooking methods such as smoking, oven-roasting, deep-frying, homebrewing, and Sous Vide and to be used while grilling. Signals is not meant to be used in place of a digital instant-read thermometer, such as a Thermapen MK4 or a ThermoPop, or used with broiling.