What kind of t-shirt does callen wear on ncis la?

In "NCIS: Los Angeles," Special Agent G. Callen, played by Chris O'Donnell, is often seen wearing fitted, casual t-shirts, typically in solid colors or simple patterns. His style reflects a laid-back yet practical approach suitable for his role as an undercover operative. The t-shirts are usually paired with tactical pants or jeans, contributing to his rugged, approachable persona.