What paper sizes can be fed through Tray 1 (single-sheet priority feed slot)?

Tray 1 supports a wide range of sizes including Letter, Legal, Executive, A4, A5, A6, B5, B6, envelopes (such as Envelope #10, Monarch, B5, C5, and DL), and custom sizes ranging from 76 x 127 mm to 216 x 356 mm. Smaller media such as 4x6 and 5x8 cards are also supported in Tray 1. (Pages 7–8)