What the resistor values do for your switching threshold
The RN1705,LF: That ratio sets the turn-on threshold: the base sees roughly 2.2 kΩ in series, so the input voltage needed to saturate the transistor is higher than a bare NPN, but the 47 kΩ to ground ensures a clean off-state with less than 500 nA leakage. Rated for 100 mA continuous collector current with a 50 V collector-emitter breakdown, it handles typical logic-level loads like relay coils, LED indicators, or small signal switching where you want to eliminate external base resistors.
The dual-transistor layout shares the emitter for both devices, common in BRT arrays for space-constrained boards. Available in tape-and-reel or cut-tape quantities for prototyping or production runs.