GF Gage G551856 #10-32 UNF 2B STI Double-End Thread Plug Gage

This is a new GF Gage G551856 (order/serial ref 55315816) double-end (DE) thread plug gage for #10-32 UNF internal threads to Class 2B tolerance, configured for STI (Screw Thread Insert / HeliCoil) oversize threads. The GO member is engraved "10-32 UNF STI GO PD .2103" and the NO-GO (NOT-GO) member is visible on the opposite end, both machined to W-tolerance (Class X) working gage limits per ASME B1.2. The STI designation means the gage checks the tapped hole that will receive a wire-thread insert (e.g., HeliCoil), which requires a larger pitch diameter than a standard 10-32 hole; the GO PD of .2103 in confirms the STI oversize. The gage ships in a clear plastic case with a GF Gage Certificate of Compliance dated 2/27/2025, traceable to NIST masters inspected in a 68°F temperature-controlled laboratory per MIL-STD-45662A, making it suitable for AS9100, ISO 9001, and defense manufacturing inspection requirements.

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