The shape and size of the baseball glove is decided by official baseball rules ; Section 1.00 , Objectives of the Game , defines limits of catcher 's , first baseman 's and fielder 's glove in parts 1.12 , 1.13 and 1.14 . The shape and size of the baseball glove is governed by official baseball rules ; Section 1.00 , Objectives of the Game , defines limits of catcher 's , first baseman 's and fielder 's glove in parts 1.12 , 1.13 and 1.14 .