Any early generation iPhone so you can't install any apps on it since all modern apps require a recent iOS. I've seen them go for as low as $25 [0]. [0] https:

Any early generation iPhone so you can't install any apps on it since all modern apps require a recent iOS. I've seen them go for as low as $25 [0]. [0] https://www.ebay.com/itm/165672302698 https://www.ebay.com/itm/165672302698