Laws of Cricket 1980 Code - Law 6
1. Width and Length
The bat overall shall not be more than 38 inches/96.5cm in length; the blade of the bat shall be made of wood and shall not exceed 4-1/4 inches/10.8cm at the widest part.
Notes
1. The blade of the bat may be covered with material for protection, strengthening or repair. Such material shall not exceed 1/16 inch/1.56mm in thickness.
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