A raglan shirt is characterized by its sleeves, which extend in one piece fully to the collar, leaving a diagonal seam from the underarm to the collarbone. This design contrasts with traditional set-in sleeves that are attached at the shoulder. A baseball tee, featuring sleeves of a different color than the body of the shirt, exemplifies a common application of this sleeve style.
The raglan sleeve construction offers an enhanced range of motion and a more relaxed fit compared to standard set-in sleeves. Historically, the style is attributed to Lord Raglan, who reportedly wore a similar design after losing an arm in battle, requiring a garment that allowed for greater ease of movement. This sleeve construction became particularly popular in sportswear due to its comfort and functionality.