The 919-104P-51A1X: It's a snap-on, right-angle, free-hanging (in-line) connector — the right-angle body lets you route the cable tight against a panel or board edge without a hard bend. The 0.1 dB insertion loss at 6 GHz is about as clean as it gets for this interface class; you won't see signal degradation in a GPS, Wi-Fi, or cellular front-end run. The gold-plated brass center pin and beryllium copper body with nickel finish hold up over 500 mating cycles, which is solid for a field-service or test-bench connector that gets swapped regularly.
This plug is built for RG-174, RG-188, RG-188A, RG-316, LMR-100, and M17/119-RG174 cables — the common thin flexible coax types used in short jumper runs. The center contact is solder-terminated; the shield is crimped. The crimp ferrule gives a gas-tight shield connection that won't work loose under vibration, and the solder joint on the pin is straightforward with a standard iron.
Lifecycle Reality — NRND
That means Amphenol RF is not actively supporting it for new projects, though existing production or maintenance runs may still draw from channel stock. There is no official replacement order code on record. If you are starting a new design, look at the current MCX offering from Amphenol RF under the base number 91910; the interface and cable groups are the same, but the specific part number may differ.