Spi 91-407-7 Feeler Gauge 0.55mm Parallel Leaf 12 Inch

Product Description

The SPI 91-407-7 is a single-leaf feeler gauge used to measure and verify precise gaps in mechanical assemblies, valve clearances, bearing fits, and similar close-tolerance applications. The leaf measures 0.55 mm in thickness, 0.5 inches wide, and 12 inches long, providing a stable, parallel profile across the full working length. Constructed from high carbon steel, the blade resists flex and wear under repeated use. This type of gauge is a standard precision hand tool used by HVAC technicians, machinists, engine mechanics, and field service professionals who need reliable gap measurement without calipers or dial indicators.

The 91-407-7 is suited for residential and commercial maintenance tasks where a specific gap specification must be confirmed or set. Typical applications include checking spark plug gaps, valve lash clearances, compressor blade clearances, burner orifice spacing, and any assembly that calls out a 0.55 mm tolerance. The parallel leaf style ensures consistent thickness from tip to blade, so measurement readings are uniform along the entire insert length. This is a single-leaf gauge sold individually.

Key Features

• Parallel leaf profile delivers consistent 0.55 mm thickness along the full 12-inch length
• High carbon steel construction provides durability and resistance to deformation under repeated use
• 12-inch leaf length accommodates deep or hard-to-reach gap locations
• 0.5-inch blade width offers a stable seating surface in standard gap applications
• Single-leaf format allows targeted use without the bulk of a multi-blade set

Compatibility

Designed as a general-purpose precision feeler gauge leaf suitable for any application requiring gap verification at a 0.55 mm specification across HVAC, mechanical, and industrial service trades.

Installation Notes

Feeler gauges are hand tools and require no installation, but proper use matters for accurate readings. Insert the leaf into the gap with light, consistent hand pressure — the blade should slide with slight drag, not bind or drop freely. De-energize and lock out any equipment before inserting a gauge into a live mechanical assembly. Do not force a blade that is too thick for the gap, as this can distort the leaf and compromise accuracy on future measurements.