Red PIDG insulated quick disconnect, 0.110" tab
The 165566-1 is a red, non-mating-end-insulated female quick disconnect from the TE Faston PIDG series, accepting 16-22 AWG wire with a 0.110" (2.79mm) tab width and 0.032" (0.81mm) tab thickness. The tin-plated brass contact is crimp-terminated for free-hanging (in-line) use, with an overall length of 0.780" (19.81mm) and an insulation diameter of 0.140" (3.56mm).
Tab width difference vs 1377175-8
The 165566-1 uses a 0.110" (2.79mm) tab width, while the same-series sibling 1377175-8 uses a wider 0.312" (7.92mm) tab — the two are not mechanically interchangeable on the same male tab, though both share tin-plated brass contacts and PIDG insulation.