#4241 High Speed Steel is perfect for drilling holes in thin mild steel, aluminum, copper, brass, Plexiglas, wood, and laminates Two flutes design for true round holes and automatically deburrs as you drill Tri-flat shank design for sure grip in chuck without slippage Set includes: 1/4" Shank: 3/16" to 1/2" holes in 1/16" steps 1/4" Shank: 1/8" to 1/2" holes in 1/32" steps 3/8" Shank: 1/4" to 3/4" holes in 1/16" steps 3/8" Shank: 3/16" to 7/8" holes in 1/16" steps 3/8" Shank: 1/4" to 1-3/8" holes in 1/8" steps .