Spot Gen4 completely sealed and waterproof to 30 metres (Kayaking)
Internal rechargeable Lithium battery with a week or 2 of life.
Wireless charging or sealed small round 5 Volt charge port with plug.
Bluetooth connection to phone for updating settings and firmware.
the small rubber isn't the best way to seal the device. My SpotGen3 was waterproof and great on 4-5 hours on the waves and similar. After a few months of using and being every day on the Sea, the batteries get corrosion so the device wasn't working anymore. My mistake was I didn't wash it from the Seawater every day but I would suggest some improvement like on GoPro MAX about "door" for the USB plug. Now I bought a new one and I will keep it always in plastic bag for anycase.