Losing sight of a wandering child on a packed summer beach or at a crowded football match is every parent's worst nightmare.
But now, the frantic search for a distraught child could be a thing of the past - simply brand your child with a temporary tattoo.
The temporary transfer tattoos can be stuck on children of any age, with just the necessary contact details to reunite them with mum and dad.
They come with a customised message containing a mobile phone number and the message "I'm lost." Now, instead of waiting for an embarrassing tannoy call or expensive search-and-rescue mission, tots will be able to show the tattoo to their rescuers.
The sticky transfers, known at "tottoos," were the brainchild of mum-of-five Virginia Lu, who came up with the idea after finding a lost child on a family day out.
When the little girl couldn't remember her mother's name or number, tearfully calling out for "Mum," Mrs Lu decided to take matters into her own hands.
She said: "With five kids of our own, we're always concerned about them getting lost or hurt when we're visiting places like amusement parks and museums.
"We had tried other things like bright T-shirts and shoe tags, but it wasn't until our chance encounter with the little girl at the football stadium that we came up with the temporary tattoo idea.
"We were at a very crowded football game and came across a crying girl standing by herself.
"She didn't know her mother's name or anything that could help us help her find her mum. We were feeling helpless, just as she did.
"My husband got a hold of the stadium security, and after what seemed like the longest 25 minutes of our lives, were we able to locate an equally hysterical woman searching around the concourse.
"One of the first things I noticed was her mobile phone was on a hip holder.
"I was thinking the whole time how worried the girl's mother must have been and wished I could have just called her to let her know where her child was, and that she was safe.
"I also thought that this sort of thing must happen all the time and it could easily have been me.
"Even what we teach the children, their home phone number, really isn't helpful when they're with their parents and get separated.
"And I was alarmed that if a lost child was very young, anyone at all could walk up and pretend to be the parent.
"That's when it occurred to me that temporary tattoos with the parent's cell phone number would be a great solution.
"It's just enough information to contact the parent, without revealing too much or putting pressure on the child to produce that information." The family-run business is based in America but can send tattoos worldwide printed in any language.
Any message can be included on the tattoos, which are also used to highlight life-threatening medical conditions.
The tattoos, which cost 18 pounds for a pack of 15, are temporary and can be washed off with soap and water.