Best/safest e-collar for a really small dog?

My boyfriend has a miniature Pomeranian that barks a lot. I live in an apartment and whenever we leave her there, she barks at every sound (we are typically only ever gone an hour). A neighbor kindly mentioned it to me the other day, and tonight when we were returning from dinner we could hear her from far down the hallway. I also have a golden retriever puppy who stays kenneled when we are gone and as of now she does not bark but I don’t want her to learn the habit or think its okay to be barking at every sound.

All of this to say, I would really like to get a bark collar for my boyfriend’s dog but the ones I’m familiar and comfortable with are geared towards larger breeds. This Pomeranian probably isn’t even a full 5 pounds and she’s 5 so definitely full grown (she does only have 3 legs so that’s part of it haha). Anyways any tips for breaking that habit and any suggestions for safe reputable and effective bark collars would be super helpful!