The 920-504J-52P: It is a single-port connector rated to 3 GHz, with a specified insertion loss of 0.1 dB — clean enough for signal paths that do not need the bandwidth of an SMPM or SMA.
The 920-504J-52P is a jack (female socket); the 920-503J-53P is its plug (male pin) counterpart. Both are HD-EFI, 50 Ohm, single-port, with the same 0.1 dB insertion loss and nickel body finish. The key difference for selection: the jack here has a limited detent and is rated for 50 mating cycles, while the 920-503J-53P is a smooth bore design rated for 200 mating cycles. If your assembly sees frequent reconnects — say a test cable that gets swapped daily — the 920-503J-53P plug with its higher cycle life is the better fit. For a permanent or semi-permanent board mount, the 920-504J-52P jack is fine and the lower cycle rating is not a concern.