just found out about this through great little trading company and wondered if anyone has one and do they really work.
i am a nervous wreck with ds2 managing to do this however tight i make the harness on the carseat. i did go to a baby shop a while ago to see if the did something to stop this happening and they said no because it could affect the baby's chest/ribcage if i had to do an emergency stop.
I have a brand new one somewhere.It is still in the packet.We had 2 and this one was a spare!.
TBH it worked really well.My son was a mini houdini until i bought this!.Let me know if your interested and i'll try and locate it!.