Dont use them and know darn near nothing about them.
I have been using a Garmin 30 for about 3 months now. I upgraded to a larger SD card and can get 5-7 days worth of my normal driving out of it. I specifically picked this one because I wanted a name brand, no gps, and the ability to turn the sound off. I purchased it the day after someone merged into my truck and then tried to file a claim with my insurance company saying I deliberately hit her.
I wish i would have bought it sooner, could have saved me lots of grief dealing with that situation.
Why no GPS?
Looks like walmart has the garmin 30 for one of the best prices at 127.99. Expandable to 64GB Micro SD card.
Amazon has it for $114. $133.59 with a 64GB card.
https://www.amazon.com/Garmin-B014W...1474987361&sr=8-1&keywords=garmin+dash+cam+30
Get one that uses a capacitor instead of a battery - the heat will destroy the battery.