Spi 13-453-6 Combination Square Blade 12 Inches 4R

Product Description

The SPI 13-453-6 is a 12-inch replacement blade for 4R combination squares, designed for layout and inspection work in trades where precise measurement is critical. The blade features a baked enamel coating that protects the graduated markings from wear and corrosion during regular shop or field use. Four graduation increments are scribed into the blade: 1/64 inch, 1/32 inch, 1/16 inch, and 1/8 inch. This range of divisions supports fine layout work alongside quick coarse measurements without switching tools. Machinists, pipefitters, sheet metal workers, and general tradespeople install this blade as a direct replacement in compatible 4R combination square heads.

This blade is suited for residential and commercial trade environments where a combination square is a daily-use layout tool. Typical applications include marking cut lines on pipe, conduit, sheet metal, lumber, and structural steel. The 12-inch length provides adequate reach for layout on standard framing members and mechanical components. The graduated markings on both sides of the blade allow readings from either orientation, which is useful in confined installation spaces.

Key Features

• 12-inch blade length for standard combination square compatibility
• 4R graduation pattern with four increment divisions: 1/64, 1/32, 1/16, and 1/8 inch
• Baked enamel finish protects markings from abrasion and light corrosion
• Single-piece blade sold individually, suitable for field replacement
• Graduated markings support both fine layout and general measurement tasks

Compatibility

Designed as an OEM-style replacement blade for 4R combination squares accepting a standard 12-inch blade.

Installation Notes

Blade replacement on a combination square is performed by loosening the locking fastener on the square head and sliding the worn blade out. Slide the replacement blade into the head channel and retighten the locking fastener to secure it before use. No specialized tools or trade licensing are required for this swap. Verify the blade is fully seated and the lock is firm before taking any measurement or marking cut lines.