We've all seen them, and some of us even display them - 'Baby on Board' signs.
Half novelty, half 'safety feature', they're a familiar sight in the rear screens of MPVs and 4x4s alike - but could they be more of a hinderance than a help?
The idea of course is that other drivers will behave more courteously and carefully upon spotting the sign, and perhaps even that they'll help paramedics in the event of an accident. A recent report says otherwise, though.
Carried out by road safety charity Brake and insurance comparison site Confused.com, the research certainly puts forward some interesting ideas - suggesting that the signs may in fact be causing problems for emergency services.
With 46 per cent of drivers leaving the sign in place even when their children are elsewhere, the report suggests that they could well be misleading to paramedics and firefighters - leading them to believe that a child is 'on board'.
What's worse, five per cent of drivers surveyed had been involved in an accident because of - you guessed it - items in car windows obscuring their view.
As such, Confused.com and Brake have issued some points to bear in mind before you make the important decision of whether or not to install one of the £3.99 plastic embellishments.
They say you should remove the 'baby on board' sign when a baby isn't actually on board; never display 'more than one' sign in your vehicle and remove the sign if it prevents you from seeing out of the vehicle.
"Baby on board signs can be incredibly helpful for emergency services at the scene of a crash, in knowing whether there's a child involved. But this help can become a hindrance if drivers display signs when their child isn't in the vehicle," said Julie Townsend, deputy chief executive at Brake.
"Worse still is the danger that can be posed by drivers obscuring their view by cluttering up windows with lots of signs. Drivers' priority should always be getting there safely, without putting themselves, young passengers or other road users a risk. That includes ensuring your view isn't obscured and you remain fully focused on the road."