Spi 91-406-9 Feeler Gauge Parallel Leaf 0.5x12 in

Product Description

The SPI 91-406-9 is a single parallel-leaf feeler gauge used to measure precise gap clearances in mechanical assemblies. Machined from high carbon steel, the leaf holds its shape under repeated use and resists wear at the measuring tip. At 0.5 inches wide and 12 inches long, this gauge provides good reach into tight clearances on engine components, valve trains, HVAC blower assemblies, and other mechanical systems where gap tolerance is critical. Technicians and mechanics rely on feeler gauges for accurate go/no-go gap checks during assembly, adjustment, and inspection tasks. The 0.50 mm (approximately 0.0197 inch) thickness is clearly marked for fast identification at the bench or in the field.

This gauge is suited for trade and industrial use in automotive, HVAC, and general mechanical service environments. The parallel-leaf design maintains consistent width from heel to tip, allowing stable contact across the full length of the measured gap. It is commonly used when checking spark plug gaps, valve clearances, bearing tolerances, and similar close-tolerance applications where a single-thickness reference is preferred over a folding multi-blade set.

Key Features

• Parallel-leaf design maintains consistent 0.5 inch width along the full 12 inch length
• High carbon steel construction resists deformation and wear during repeated gap checks
• 0.50 mm nominal thickness provides a precision reference for close-tolerance measurements
• 12 inch length allows reach into deep or recessed assembly points
• Single-leaf format for quick identification and use without sorting through a multi-blade set

Compatibility

Designed as a general-purpose parallel-leaf feeler gauge suitable for automotive, HVAC, and industrial mechanical service applications requiring a 0.50 mm gap reference.

Installation Notes

Feeler gauges are hand tools and require no power source or special installation. Ensure the surfaces being measured are clean and free of debris before inserting the leaf to avoid false readings. Apply light, consistent drag pressure when checking fit — the leaf should slide with slight resistance at the correct clearance. Do not bend or force the leaf into a gap smaller than its rated thickness, as this can permanently deform the steel and compromise measurement accuracy.