Starrett 56366 12 Inch Combination Square Set 2 Piece 4R

Product Description

The STARRETT 56366 is a 2-piece combination square set built for layout, measuring, and inspection work in the trades. The set includes a 12-inch steel blade and a cast iron square head calibrated to 4R graduation, providing four scales: 1/64, 1/32, 1/16, and 1/8 inch. That level of graduation resolution supports precise scribing and marking on metal, wood, and pipe. The cast iron head delivers the mass and rigidity needed to hold position under repeated use on a job site or shop bench. At 1.25 pounds, the set is light enough to carry on the tool belt but solid enough for consistent reference work.

This combination square set is suited for use by pipefitters, millwrights, sheet metal workers, electricians, and general construction tradespeople who need a reliable layout tool. It performs well in fabrication shops, mechanical rooms, and field installs where accurate 90-degree references and depth measurements are part of standard workflow. The 12-inch blade length covers most common layout tasks on conduit, ductwork, structural members, and panel work.

Key Features

• 12-inch steel blade with 4R graduation (1/64, 1/32, 1/16, and 1/8 inch scales)
• Cast iron square head provides rigid, stable 90-degree reference
• 2-piece set includes blade and square head
• Metric-equivalent graduations: 0.02 in, 0.03 in, 0.06 in, and 0.13 in increments
• Compact 1.25-pound weight for field portability

Compatibility

Designed as a standard 12-inch combination square set suitable for general layout and inspection applications across HVAC, plumbing, electrical, and mechanical trades.

Installation Notes

No power source or lockout procedure is required for layout tools. Inspect the blade lock mechanism before use to confirm the blade holds position under scribing pressure. Store the set in a dry location to prevent corrosion on the steel blade and cast iron head. Periodic cleaning of the blade slot and locking screw ensures consistent clamping force over time.