BTH-550-MAX Bluetooth Wireless Noise Canceling Speaker Microphone with ROTARY Volume Control and Built-in Wireless PTT (Push-To-Talk) BTH-550-MAX Bluetooth Wireless Speaker Microphone with Rotary Volume Control is smaller and lighter than our BTH-600-MAX, but still just as weather-resistant. It has a ROTARY VOLUME CONTROL, which can be much easier to use, especially when wearing gloves. With more than 40-hours of talk time (80-hours typical) and greater than 30-days standby time, the BTH-550-MAX is a real workhorse. The PRYMEMAX version works on cellphones, tablets (iOS and Android), plus many two-way radios that have built-in Bluetooth including Icom, Kenwood, EFJ and BK. It is also compatible with all PRYMEBLU radio adapters including the new V2 versions. Other features include a waterproof front-facing speaker, directional noise-canceling microphone, heavy-duty clothing/belt clip that swivels 360 degrees, and strategically-placed pairing and low-battery warning lights on top of the microphone, and super easy to use. This industrial-strength unit is multi-functional, featuring a broad-range ROTARY volume control, 3.5mm earphone jack, rechargeable battery (comes with universal USB wall charger and cable) and can be paired with either Android or iOS Apple tablets or cellphones. The side button activates PTT (push-to-talk) function while the top button controls normal phone functions (answer, hang-up, etc.) Features Charging Dock Drop-in ChargerWith more than 40-hours of talk time (80-hours typical) and greater than 30-days standby timeWeather-resistant Volume Control Industrial-strength unit is multi-functional, featuring a broad-range ROTARY volume control3.5mm Earphone JackStrategically-placed pairing and low-battery warning lights on top of the microphone, and super easy to use Clothing Clip Heavy-duty clothing/belt clip that swivels 360 degreesPTT (push-to-talk) function while the top button controls normal phone functions (answer, hang-up, etc.) Charging Cable Comes with universal USB wall charger and cableWorks with cellphones, tablets (iOS and Android), plus many two-way radios that have built-in Bluetooth The BTH-550-MAX speaker microphone has an internal Lithium-Ion rechargeable battery pack which must be charged prior to operation, and must be recharged regularly. A fully charged battery will provide up to 40 hours of continuous operation before needing to be recharged. However, operating time can vary depending on usage and the condition of the battery pack. Recharge the battery regularly. The microphone can be charged either using the wall charger. Rotary Volume Control also works as on/off switch and push-to-talk feature works with apps such as ZELL0, ESChat, Wave Communicator, Streamwide, and Unity. Typical operation range: 10 meters Talk time: 40+ hours. Standby 30 days For use w/PRYMEBLU radio adapters, ICOM and KENW radios w/built-in Bluetooth Any standard 3.5mm listen-only earphone can be plugged into accessory jack including Apple earphones Top blue button is used to place mic into pairing to connect to Bluetooth adapter or 2-way radio Dust and water resistant to IP56 levels