The 4-1761185-1: It is not a standard RJ45 — the SDL form factor is a narrower, keyed variant used primarily in telecom central-office and customer-premises equipment where space on the line card is tight and the connector must resist accidental insertion of a standard RJ11 or RJ45 plug. The 4 positions match 2-pair signal wiring typical of POTS (plain old telephone service) or ISDN line interfaces. The shielded construction bleeds common-mode noise from the twisted-pair cable before it reaches the line transformer, which is why you see this jack on DSL filters, PBX backplanes, and demarcation blocks.
Through-hole solder tails give the shield and the signal pins a mechanical anchor that surface-mount variants lack — important when the cable is routed through a crowded cabinet and the jack sees side-load from the patch cord. The board guide (a pair of plastic alignment posts) locates the part during wave-solder assembly and takes the shear off the signal pins when the plug is inserted or yanked. The keyed housing prevents a standard 6-position or 8-position plug from being forced in, which would short the line-side pairs to the chassis ground through the shield.
That thickness of gold is well into the field-grade range — it is not a flash coating.
Shielding and Environmental Range
Operating temperature range is -20°C to 80°C.