Recommendations on sleep positioners?

[CAM123]

Looking for advice / recommendations on sleep positioners. Seen so many different styles (at Mothercare, JoJo Maman Bebe etc).

Not sure what the priorities should be - to go for one with a head support / wedge or a simple design with just the two side-bars, what material (presumably which is most breathable, but so many seem to be foam), decorated or simple, adjustable or not?

Would really appreciate any advice as models and prices vary massively.

Thanks!

Why do you need one?

Thought they were the standard these days - you know the thingies that keep the baby in position in the cot, so they don't roll onto their sides / backs / all over the place.

Cam, they're meant to be on their backs!

I never had one, dd survived

Sorry, yes I mean 'so they don't roll onto their sides / fronts' and stay on their backs!