Spi 91-403-6 Feeler Gauge Parallel Leaf 12 in

Product Description

The SPI 91-403-6 is a parallel-leaf feeler gauge used to measure small gaps and clearances in mechanical assemblies. The leaf measures 0.5 inches wide and 12 inches long, constructed from high carbon steel for durability and resistance to deformation under repeated use. Feeler gauges of this type are standard tooling in HVAC, engine, and mechanical service work where precise gap measurement is required. Technicians use them to check valve clearances, spark plug gaps, burner orifice spacing, and similar tight-tolerance applications. The single-leaf format provides a clean, unobstructed reading surface without the bulk of a folded set.

This feeler gauge is suited for residential and commercial service environments where accurate gap measurement is part of routine maintenance or commissioning. Typical applications include checking heat exchanger and burner alignment, motor bearing clearances, and component fitment verification during installation or inspection. Its 12-inch length allows access into deeper assemblies where shorter gauges may not reach.

Key Features

• Parallel leaf style provides uniform thickness across the full length for consistent measurements
• High carbon steel construction resists bending and wear under repeated use
• 0.35 mm (approximately 0.014 inches) nominal thickness for precise gap checking
• 12-inch leaf length allows access to recessed or deep assemblies
• 0.5-inch width gives a stable, easy-to-handle surface

Compatibility

Designed as a general-purpose feeler gauge for use in HVAC, mechanical, and light industrial service applications where gap measurement to 0.35 mm is required.

Installation Notes

Feeler gauges are a hand measurement tool and do not require installation. De-energize and shut down any equipment before inserting the gauge into rotating or pressurized assemblies. Apply light, even pressure when sliding the leaf into a gap — forcing the gauge can cause permanent deformation and an inaccurate reading. Store the leaf flat to prevent warping that would compromise measurement accuracy.