Are TENS machines all much of a muchness?

[Cattleprod]

I borrowed a tens machine for the birth of DS, which I found really helpful for the first few hours of labour. I'm thinking of buying one for the next baby, but I know very little about the different sorts available.

Should I just get whatever sort is on special offer? Or are there any features that would be useful, or any good brands, or brands to avoid?

Thankyou!

[Tangle]

I used an Elle TENS for both DD1 and DD2 - I liked the way I could tweak things and I'd used it again.

Things I'd look for if I were buying a TENS would be:

• designed for maternity use, which usually means two channels on 4 pads
  
• ability to change settings for each channel separately
  
• boost function (good during contractions)