Spi 91-371-5 Feeler Gauge 0.018 in Parallel Leaf 12 in

Product Description

The SPI 91-371-5 is a parallel-leaf feeler gauge used to measure small gaps and clearances with precision. The leaf measures 0.018 inches thick, 0.5 inches wide, and 12 inches long, providing a consistent cross-section along the full length for reliable readings. Constructed from high carbon steel, this gauge delivers the hardness and surface finish required for accurate feeler measurement work. It is used by HVAC technicians, machinists, and trade mechanics who need to verify valve clearances, spark plug gaps, bearing clearances, and similar tight-tolerance fits. The parallel leaf design means the thickness is uniform from tip to base, which eliminates taper-related measurement error.

This feeler gauge is suited for residential and light commercial maintenance applications, engine and equipment service, and general mechanical fitting work. Technicians reach for individual-leaf gauges like this when a specific thickness is needed without carrying a full set, or when the job requires a longer blade to reach into confined areas. The 12-inch length makes it practical for deep clearance checks on compressors, blower assemblies, and burner components where a short blade cannot reach. A single-leaf format also allows quick pairing with other gauges to build a combined thickness stack.

Key Features

• Parallel leaf profile ensures uniform 0.018-inch thickness along the full 12-inch length
• High carbon steel construction provides hardness and resistance to deformation under use
• 0.5-inch blade width gives a stable, easy-to-read contact surface in most clearance checks
• 12-inch length reaches deep into assemblies where shorter gauges cannot seat properly
• Single-leaf format allows stacking with other gauges to measure non-standard clearance thicknesses

Compatibility

Designed as a general-purpose parallel-leaf feeler gauge suitable for gap and clearance measurement across HVAC, mechanical, and equipment service applications.

Installation Notes

Feeler gauges are a hand-measurement tool and do not require installation in the traditional sense. Before taking a clearance measurement, power down or lock out any equipment being serviced in accordance with applicable safety procedures. Insert the gauge leaf with light, consistent hand pressure — forcing the blade can spring the leaf and introduce permanent deformation that compromises accuracy. Store the gauge flat and clean to prevent bending and surface corrosion that would affect readings.