With these Wirecutter-approved picks under $100, you don’t have to spend a lot to get a good deal this Amazon Prime Day.

Amid this growing threat, Amazon made crucial changes to its annual Prime Day sale, which started on July 8, to attract more customers. First, it extended the sales event to four days; last year it was only two days long. Amazon has also ramped up advertising of the event’s steep discounts.

If you’re a Prime member, you can save up to $100 on the waterproof e-readers.