The 10.5-inch Pro, where ProMotion debuted at up to 120Hz and the screen grew 20% without the body growing much.
Released June 13, 2017 · Discontinued October 30, 2018 · From $649 (64 GB, Wi-Fi)

An odd size, quietly missed. Apple built a 10.5-inch Pro by shrinking the 9.7-inch model's bezels, making the screen 20 percent larger in a body barely bigger, and it is the first iPad that could show a full-size onscreen keyboard without cramping. ProMotion debuted here, an adaptive refresh rate up to 120Hz that makes scrolling and Apple Pencil latency feel immediate rather than merely quick. The A10X Fusion was faster than most laptops Apple sold. This is the generation where the iPad Pro started to make a serious argument, two years after the first one asked the question.
The first ProMotion display at 120Hz was the standout, in a body barely larger than the 9.7-inch model it replaced.