3" 18TPI T-Shank Metal Cutting Bi-Metal Jig Saw Blades 5PK

What it is:

The 48-42-5121 is a Milwaukee 3-inch 18 TPI bi-metal T-shank jig saw blade set (5-pack) made for metal cutting. It is the modern T-shank equivalent to the older U-shank metal blade styles you asked about earlier.

Key specs:

• Blade length: 3 inches
• Teeth per inch (TPI): 18
• Material: Bi-metal
• Shank type: T-shank
• Pack quantity: 5 blades
• Best use: Metal over 1/8" thick

Key features:

• Bi-metal construction: Longer life than carbon steel or standard HSS blades
• 18 TPI tooth pattern: Good balance of speed and cut quality in metal
• Fast shearing action: Designed for clean cuts in steel and sheet metal
• T-shank fitment: Quick-change compatibility with most modern jig saws

In plain terms:

This is your general-purpose metal jigsaw blade for newer saws.

Best for:

• sheet steel
• conduit
• light plate steel
• angle aluminum
• thin pipe

Compared to your other blades:

• 48-42-2160: thinner metal / finer finish (24 TPI)
• 48-42-5121 (this): medium metal / balanced cuts (18 TPI)
• 48-42-2190: thicker metal / more aggressive (14 TPI)

So this one sits right in the middle of the metal-cutting lineup.

Simple takeaway:

• 48-42-5121 = metal-cutting T-shank blade
• 18 TPI = balanced speed + smoothness
• Best for metal over 1/8"
• Great everyday blade for general fabrication and electrical work