Designed and manufactured for the professional user. Detail to the material used, tooth shape and sharpness makes these blades cut clean, fast and have a longer life. No. 48-42-5101: Style: T-Shank, Material: High Speed Steel, Length: 3 In., Teeth Per Inch: 14 TPI, Application: Metal, Pkg Qty: 5, Package Type: Card No. 48-42-5240: Style: T-Shank, Material: High Carbon Steel, Length: 4 In., Teeth Per Inch: 10 TPI, Application: Wood, Pkg Qty: 5, Package Type: Card No. 48-42-5540: Style: T-Shank, Material: High Carbon Steel, Length: 4 In., Teeth Per Inch: 10 TPI, Application: Downcut Wood, Pkg Qty: 5, Package Type: Card No. 48-42-0240: Style: U-Shank, Material: High Carbon Steel, Length: 3-1/8 In., Teeth Per Inch: 8 TPI, Application: Wood, Pkg Qty: 5, Package Type: Card No. 48-42-0540: Style: U-Shank, Material: High Carbon Steel, Length: 4 In., Teeth Per Inch: 10 TPI, Application: Wood, Pkg Qty: 5, Package Type: Card No. 48-42-0640: Style: U-Shank, Material: High Carbon Steel, Length: 4 In., Teeth Per Inch: 10 TPI, Application: Wood, Pkg Qty: 5, Package Type: Card No. 48-42-0101: Style: U-Shank, Material: High Speed Steel, Length: 2-3/4 In., Teeth Per Inch: 14 TPI, Application: Metal over 1/4" Thick, Pkg Qty: 5, Package Type: Card No. 48-42-0120: Style: U-Shank, Material: High Speed Steel, Length: 2-3/4 In., Teeth Per Inch: 18 TPI, Application: Metal over 1/4" Thick, Pkg Qty: 5, Package Type: Card No. 48-42-0140: Style: U-Shank, Material: High Speed Steel, Length: 2-3/4 In., Teeth Per Inch: 24 TPI, Application: Metal over 1/4" Thick, Pkg Qty: 5, Package Type: Card