i don’t have a recommendation but my antenatal classes told me that it has to be a labour specific one due to the frequency etc
The boots maternity one
I got one from Amazon, https://amzn.eu/d/68EjIIl
I also rented an Elle TENS one from Amazon https://amzn.eu/d/bxmOmnr xx
I used one already at the hospital
I used the Boots maternity one - bought the machine second hand off FB for £10 and fresh pads from Boots
I have rented one from home birth supplies and went for the Elle TENs d