Four historically significant baseball bats showcased in the National Baseball Hall of Fame's traveling exhibit "Baseball As America". From left to right: bat used by Babe Ruth to hit his 60th home run during the 1927 season, bat used by Roger Maris to hit his 61st home run during the 1961 season, bat used by Mark McGwire to hit his 70th home run during the 1998 season, and the bat used by Sammy Sosa for his 66th home run during the same season.
Many players "bone" their bats, meaning that before games, they rub their bats repeatedly with a hard object, believing this closes the pores on the wood and hardens the bat. Animal bones are a popular boning material, but rolling pins, soda bottles and the edge of a porcelain sink have also been used. Pete Rose had his own way of hardening his bats: he soaked them in a tub of motor oil in his basement then hung them up to dry.