Like other reviewers said, this turned out to be a bit narrower than I expected. Internal measurements are about 3" deep (top to bottom) X 8" long (end to end) but, as you can see from the photo of it, the end pieces slope inward at the bottom so the length at the bottom is more like 6". The significant (to me) measurement is front to back - less than 2".
I have a dishwasher that's made by Whirlpool. Neither it nor any other diswasher I've ever had requires this odd shape. I can only assume this basket is made to fit the rack of a specific and unusually shaped Whirlpool model rack.
The front and back walls of the basket warped inward slightly after a couple of wash cycles. Odd, since it is intended to be in a hot dishwasher specifically, but its ability to lock shut or hold small items isn't affected so I guess you'd call it just a cosmetic problem.
I sill like the basket, but I do wish it were about 1" wider and 1" taller.