Kiwi's answer to wet beds is a big seller at home and abroad.
Bedwetting is a tricky subject to broach in polite conversation, but it's hard to write about one of New Zealand's fastest growing companies without being potty-mouthed.
Brolly Sheets has grown its revenue by nearly 300 per cent in the past three years, thanks to its waterproof "breathable" cotton slips, which go over the bottom sheet, rather than under.
It's an important distinction because it's much easier to make the bed after a mishap if you're only taking off the top layer. It also saves on laundering.
Diane Hurford founded the company in 2006, spurred by the popularity of her product - which she devised out of frustration with the alternatives - at the local playcentre.
Word of mouth is always important to start-up companies but it's interesting that, six years on, this multimillion dollar exporter still generates 40 per cent of new orders from referrals. Now she is also selling the sheets and related products in Australia and Britain, and will launch an online campaign in the US next week.
Bedwetting is big business. Recent statistics show that 4.2 million babies are born each year in the US; in Britain it is 650,000, and 295,000 babies are born in Australia, the company's biggest market. A good proportion of those little nippers have a good year, if not two, of needing bedwetting protection.
"We're still growing in the children's market [in Australia] and the UK has taken a little while to get up," says Hurford.
She has now hired a British agent to promote her wares and is confident sales in Britain will pick up. Even so, Brolly Sheets was the 24th fastest growing company in NZ last year, according to the Deloitte Fast 50 list, and the vast majority of its revenue came from overseas sales.
Aside from the over-sheet innovation, Hurford notes that most bedwetting products seem not to cater to male biology, which often involves an upward trajectory. Her company also makes an upper cotton sheet to meet that need.
But it's not just young ones who need Brolly Sheets' wares. The mature market - senility, Alzheimer's, kidney disease, dementia, pelvic floor muscle issues, prostate gland problems, etc - is huge. Unlike ankle-biters, these people don't grow up and get over it. Many will need Brolly Sheets until they die.
This is a market that is exponentially increasing as Western societies, in particular, enjoy ever more retirement years.
Hurford cites statistics: in Britain, 4.8 million people suffer incontinence and 10 million have "special needs"; 4.5 million Americans are "non-institutionalised" sufferers of kidney disease and there are 75 million people aged over 75.
If she was to distil the experiences of these many millions of people with minor but significant life issues, she would put it this way: "They need to get a decent night's sleep."
Isn't that the heart of it? Whether you're suffering dementia, you're the carer of someone whose mind has gone - or, frankly, just trying to get along without wetting the bed - the survival of this experience is all about a decent night's sleep.
Hurford speaks movingly of some of her clients, including the mothers of adult handicapped children dealing with everyday, extremely distressing, issues.
Not to be cold-hearted, but this is a column about incredible NZ companies that are making pots of cash through hard work and innovation. Hurford really has done the work. It's interesting to hear her take on Asian manufacturing. Rather than a cheap substitute for Kiwi labour - although it is much cheaper - she talks about the collaborative process with her Chinese suppliers.
In a fast-moving manufacturing world she's been able to collaborate to make new products, talking about what her market needs, rather than a per-widget price, she says. They have been equal partners, in terms of making the new product. She looked at Australia but it was more expensive than NZ, and China has proven an innovative, fulfilling partner in making Brolly Sheets a success, says Hurford.
It's not often you hear such frank acknowledgement of the benefits of working with China.