Baseball Thumb Guard Guide

A thumb guard is a shaped piece of flexible material with a loop or band that holds it on the thumb. The body of the guard sits in the web between the thumb and the first finger, against the handle, so that the handle rests on the guard instead of on the joint at the base of the thumb. It adds nothing to the bat, which is why it is an accessory and not equipment the bat rules describe.

Bass makes two. The BASS THUMBLOCK is recorded as a compact, lightweight guard whose shape "sits between the hand and bat to help reduce unwanted pressure while maintaining a natural grip". The Hawk Butterfly Thumbguard is recorded as lightweight and flexible, fitting around the thumb "to help reduce sting, pressure, and discomfort during swings and contact".

Most hitters wear a thumb guard on the top hand, the hand nearer the barrel, because that is the hand whose thumb takes the handle's pressure through contact. Some prefer it on the bottom hand, and a few try one on each. Which hand is a matter of where the hitter feels the handle, and the sensible way to decide is to hit with it in each position for a round and keep the one that disappears.

The guard goes on before the batting glove is fastened if it is worn under the glove, or over the glove's thumb if it is worn on top. Either way, the loop should be seated so the body of the guard lies in the web of the thumb and does not ride up toward the tip.

• Pressure. Contact, and especially contact off the handle or the end, drives the handle into the base of the thumb. A guard takes that pressure on itself rather than on the joint.
• Sting. The same mishits send vibration through the handle into the hand. The Butterfly Thumbguard's record describes reduced sting and pressure as what it is for.
• Grip. A guard fills the gap between the thumb web and the handle, which encourages the bat to sit in the fingers. Hitters who tend to bury the handle in the palm often find the guard changes that without a thought.
• Consistency. A hitter who stops flinching from contact grips the same way on every pitch, which is the point.

A thumb guard fits when it stays put. Through a full swing the body of the guard should not rotate around the thumb or ride toward the tip, and the loop should be snug without leaving a mark. Both Bass guards are listed in one adult size; the flexible band is what accommodates the hand.

• Slide the guard on with the body in the web of the thumb, facing the handle.
• Take the grip. The handle should rest on the guard, and the guard should feel like part of the hand, not something between the hand and the bat.
• Swing. If the guard has moved, reseat it lower on the thumb. If it moves again, it is the wrong size for the hand.

Both Bass guards are recorded for baseball and softball hitters, and the piece works the same way in either game: the handle is a handle. Softball hitters swinging heavier or longer bats often notice the pressure at the base of the thumb more, not less.