How many microphones does the Jabra Speak2 75 have, and what size is its speaker?

It has 4 beamforming microphones and a 65 mm speaker.

What wireless and wired connection types does the Jabra Speak2 75 support?

The Jabra Speak2 75 supports Wireless Bluetooth, USB-C, and USB-A connectivity.

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Jabra Speak2 75 Speakerphone - Wireless Bluetooth - Zoom - 4 Microphone(s) - 65 mm Speaker(s) - Dark Gray - 2775-209-01

Forget everything you think you know about portable speakerphones. We're tearing up the rule book with super-wideband audio1, and an advanced full range 65mm speaker. This cutting-edge tech puts you front and center, unscrambling the widest range of frequencies in your voice's natural range. It's a dramatically more powerful audio experience.
Some speakerphones don't allow both sides to speak and be heard at the same time, but we think conversations are better when they flow naturally. Speak2 75 is engineered with advanced full duplex audio, with a supercharged chipset that goes way beyond standard speakerphone performance. So your conversations can flow freely in both directions, just like they would in person.
With four state-of-the-art beamforming microphones, and the very latest digital signal processing algorithms, Speak2 75 effortlessly harnesses every change in voice tone, so every nuance is picked up (because it's not what you say, it's how you say it). Innovative noise reduction technology keeps background distractions at bay. The result is an outstanding audio performance that's truly unmatched.