"Diabolica", the noisemaker of choice at the next World Cup games in Brazil, is a compact, Belgian-made instrument gearing up to replace the South African horn, moving over vuvuzela.
Its young designers said they are "overwhelmed by the flood of orders coming from all over the world", and predict that a million models will be sold by the time the month-long tournament starts on June 12.
Unlike the long, plastic vuvuzela -- whose love-it-or-hate-it drone went global at the last World Cup in South Africa in 2010 -- the "diabolica" is easier to carry, collapsing to 12 centimetres (five inches), and easier on the ear, its creators contend.
But he and partner Fabio Lavalle, 26, won't reveal the "secret" they say makes the difference.
The trumpet is already a big hit in Belgium, where stadiums ban both vuvuzelas and, for safety reasons, canister fog horns, an extremely loud, pressurised device more at home as part of a safety kit on boats.
"We never expected such a success," said Dos Santos.
Nearly 300,000 "diabolicals" -- named after Belgium's "Red Devils" football team -- have been sold since the end of last year and to keep up with demand, some 15,000 make their way daily from a Madrid factory to the plant in the southwestern Belgium city of Mons where they are assembled and packed for shipment.
"It was actually a Spanish friend, a Real Madrid fan, who came up with the idea after a friend was blocked from the stadium with a canister fog horn," said Dos Santos.
"He thought about how birds make sounds, manipulating vibrations against membranes, and he tested thousands of membranes before finding the right one."
"This membrane is the secret," said Dos Santos, who owns the patent.
- Not a new vuvuzela -
The Belgian instrument has a higher pitch, more like a horn, and can make a trilling sound when the stem is pumped. At 98 decibels, it is nearly as loud as a vuvuzela but requires less lung power, its makers say.
While voted the 2010 World Cup "word" by global linguists and "South Africa's 12th language", detractors likened vuvuzelas to a swarm of angry bees.
Doctors warned of hearing loss, broadcasters said they disrupted transmission, some players could "not concentrate" and football's world and European governing bodies FIFA and UEFA later banned it at many games.
Dos Santos brushes off concern about his product, which sells at nine euros ($12) and comes in all the colours of World Cup countries.
It is now available "across Europe, notably in Belgium, but is also huge in Portugal", he said.
And "this week we got orders from Ecuador, Mozambique, Colombia and Angola," said Fabio Lavalle, owner of the small, 14-employee Mons factory which he said is working 16 to 18 hours a day to cope with the orders. "It just doesn't stop."
Ironically, a Brazilian-made rival, the "caxirola" -- a yellow and green plastic percussion instrument resembling a hand-grenade that rattles when shaken -- created to be the official instrument at the 2014 games has since been banned.
Brazilian supporters used caxirolas to attack players in a local match before last year's Confederations Cup, prompting the government to ban both caxirolas and vuvuzelas from those games.
Brazil has said the caxirola, and any object that could be used as a weapon, will not be allowed into 2014 World Cup games, but so far -- like FIFA -- has no official position on the ?diabolica? or the vuvuzela other than to say it could be banned if it?s deemed to be an object that could be used in violent acts
Dos Santos remains confident, showing off photos with football stars like Brazilian striker Ronaldo, Michel Platini or Luis Figo checking out his product.
"We met Ronaldo in Madrid a few weeks ago for a charity match and he tested the 'diabolica'. He didn't want to give it back to us," he joked.
"Believe me, the 'diabolica' is going to make a lot of noise this summer in Brazil."