Inside their baseball hats, pitchers usually don’t stash anything “illegal,” but they may carry a mix of tech, reminders, and habit‑driven items.

PitchCom earpiece and tech

Since 2023, many MLB pitchers wear a small PitchCom receiver earpiece tucked under the cap that lets them hear the pitch call from the catcher’s wristband‑style transmitter.

This helps cut down on sign‑stealing and speeds up the game, but umpires can still ask to inspect the hat to make sure nothing else is hidden.

Notes and scouting reminders

Some pitchers keep a small card or folded paper in the hat brim with:

  • A quick scouting reminder for certain hitters.
  • Location or pitch‑type cues they like to glance at during a stoppage.

This isn’t required by the rules; it’s more of a personal routine or mental‑focus trick.

Sweatband and comfort items

Many hats also have an internal sweatband or moisture‑wicking liner that soaks up sweat and keeps the sun out of the eyes.

Some pitchers or teams have tested padded protective caps with extra padding or inserts to help reduce head impact risk without changing the standard look too much.

Why umpires check the hat

After mound visits or stoppages, umpires sometimes ask to see the pitcher’s hat, glove, or belt to verify nothing foreign (like grip‑enhancing substances) is being hidden or transferred to the ball.

The rulebook bans anything that materially affects how the ball leaves the hand, so these checks are mostly about enforcing that “no sticky stuff in the hat” standard.

In short: what’s usually in a pitcher’s hat is a legal earpiece, maybe a tactical note, plus standard sweat‑absorbing fabric and sometimes protective padding —not anything illegal.

Information gathered from public forums or data available on the internet and portrayed here.