ADS AGS3910
Dimensions for Close Tolerance Tapped Bosses with Unified Threads for Pipe Coupling Union Adaptors using Pipe Fitting 'O' Ring Seals, eg. AS43003. (Recommended for use with pressures above2500 lbf/in2. For pressures up to 2500 lbf/in2, AGS 3911 recommended)
Data Sheet by SAE ITC TSC Aerospace Standards (Formerly ADS Group Limited), 07/01/1974