What connectivity and device compatibility does this printer offer for setup and use?

It supports USB, Bluetooth, MFi, and NFC pairing, and is compatible with PC, Mac, Android, Windows, and Apple iOS devices.

What print width and print speed does the Brother RuggedJet RJ4235B support?

The Brother RuggedJet RJ4235B supports a 4 inch print width and prints at up to 5 inches per second in monochrome.

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Brother RuggedJet RJ4235B Mobile 4 DT Printer w/USB, BT, MFi, NFC Pairing - 4" Print Width - 5 in/s Mono - 203 dpi - ZPL, CPCL Emulation