Over the years, many people speculated that Mickey Mantle had an extra advantage late in his career by corking his bat. Now, there may be some evidence behind it.

Someone x-rayed a bat Mantle used in 1964, and it appears the bat was hollowed out.

One of the experts who examined the bat found a circular area almost an inch wide in the center of the top barrel of the bat.

"The finish in the area has also been touched up to mask the circular area," the expert said. "Alterations of this nature indicate the barrel has been drilled and filled with cork. We had the barrel x-rayed, and [it] confirms that the barrel has been drilled and filled with cork."

The bat is going up for auction later this month with an opening bid of $5,000.

Corking a bat allegedly gives a batter's swing more speed without sacrificing power.

Mantle retired in 1968.

Read more: LA Times