Best Doppler?

Hey ladies I’m 7+1 today and I’m gonna get myself a fetal Doppler. Saw bubs heart beating away a few days ago and I’m super excited to be able to hear it in the 5/6 weeks I have to wait for a scan again, a little reassurance! I know I won’t hear anything as of yet but I have some questions!

Which is the best fetal Doppler?

When will I begin hearing a heartbeat?

Is it safe and how often can I use it?

Thanks very much girls! First time mum after 2 losses last year ❤️