Kindle - but the OLD style one, the 4th gen E-ink version, with buttons instead of swiping for page turns.

The one I have now, I bought it used on Ebay about 6 years ago. The battery is starting to go, it doesn't last long anymore. It used to last a seriously long time, even with a lot of reading - like a month or so.

I'm happy that it has the e-ink screen, even though I need a light to read, it's not back lit. It's a more natural form of lightning.