These Mortising Chisels aregreat for drilling square holes in wood with a mortising machine or a mortising attachment (not included). Set of 4 includes the following sizes: 1/4", 5/16", 3/8" and 1/2". This quality set also comes with a convenient plastic storage case. Specifications 1/4" Wide 5/16" Wide 3/8" Wide 1/2" Wide Plastic Storage Case Included 3/4" Collar