and this is more detailed:
The Best Buy Britax BABY-SAFE SLEEPER is the first 'lie-flat' child restraint system we've tested that protects the child well in a crash.
It is designed to carry babies from newborn up to 10kg. All the seats and carry-cots designed to carry babies lying down that we've previously assessed have been very tricky to install. And they have usually been found wanting, with major weaknesses in a front crash, side crash or both.
In contrast, this system, which sits across the rear seat of the car, secured using the three-point seatbelt, offers five-star crash protection in both front and side impacts.
Installing the Britax Baby Safe Sleeper is quite a complicated process compared to conventional child seats for this age group, but it has clear instructions and good warning labels, minimising the danger of it being installed incorrectly.
The baby travels in a well-padded, comfortable restraint and, to help cope with the normal spillages and leaks associated with newborns, the cover is easily removed and fully machine washable.
Britax has sensibly decided not to try and make the Baby Safe Sleeper work as an upright seat (which might have compromised its overall performance), but this means you ll have to purchase another seat as soon as you want your child to start travelling in an upright, seated position.
The Britax Baby Safe Sleeper seems to address many of the concerns about transporting newborn babies safely.
Pros: A safe, comfortable solution for anyone wishing to carry their newborn in a lying down position
Cons: Cannot be used to carry children sitting up. Limited to use by very young babies (up to 10kg)