Fish premium hollow Mortise and Chisel sets are constructed of special steel and are used for drilling and mortising square holes in soft and hard woods. Fits all mortising machines and drill press attachments. 4 Piece set includes 1/4-Inch , 5/16-Inch , 3/8-Inch , and 1/2-Inch sizes. Made in Austria. Diameter on each chisel in the 4pcs set is 5/8. The depth of each chisel is below: 1/4" Chisel 1-3/4 Depth, 5/16 Chisel 1-3/4 Depth, 3/8 Chisel 3 Depth, 1/2 Chisel 3 Depth.