Doppler recommendations

Nena • 👧🏼• 👶🏻

Which dopplers are good? Where can I order one from? I would only use it here and there not on a daily basis. I’ve had a loss before and this is the furthest that I’ve carried, I’m 11+1 and I know it’s still early but I’d like to get one for the future. Also do y’all have any tips and tricks to using one? TIA ☺️