As Harry Potter and the Deathly Hallows: Part 2 gets its first screening at midnight tonight, Lochaven International workers will get the chance to see the costumes they provided for the film series.
They are worn in the epic fight at the school involving Harry and his friends and the evil Lord Voldemort, during the new film's climax.
Company director Colin Leishman, 36, said: "There is a huge battle scene at the end and everybody was wearing our jumpers. It's fantastic.
"It's been very good for us. We are not a huge company, but it has certainly put the turnover up a bit."
Harry Potter has certainly cast a business spell on the textile firm, which was going into liquidation three years ago but has sold more than 20,000 jumpers to fans around the world. The company has made a mammoth 3500 lambswool jumpers for seven films, starting with the second movie, Harry Potter and the Chamber of Secrets, which came out in 2002.
They have been worn by lead characters Harry, Ron and Hermione, played by Daniel Radcliffe, Rupert Grint and Emma Watson, as well as the hundreds of other actors and extras who play Hogwart pupils.
The jumpers, as well as tank tops and cardigans are all detailed with the different colours of the Hogwarts School houses – burgundy for Gryffindor, yellow for Hufflepuff, blue for Ravenclaw and green for Slytherin.
Each has 'Lochaven' and 'Made in Scotland' on the label and they are all made at the Stewarton factory by the firm's 21 staff.
And while the premiere of the final film reduced author JK Rowling and actress Emma Watson to tears, the firm is also sad to wave goodbye to Harry as the eighth and final film is released.
Mr Leishman added: "Its been great having them in the films, and it's just a pity this is the last one.
"But though it's the end of the films, we have still got the franchise, which is going to continue for a long time. They're the biggest films ever, bigger than Star Wars."
Because the child actors kept growing, every year the company would receive requests for hundreds of new jumpers. Individual measurements were sent up, and each jumper was tagged with the name of the actor.
Potter fans have also been able to buy the jumpers, from £49.99, on the firm's website for the past few years.
The company holds the worldwide licence from Warner Brothers, and also makes jumpers sold at the Wizarding World of Harry Potter theme park at Universal in Orlando.
It will also supply them to shops at a new Harry Potter attraction at Leavesden Studios in Hertfordshire, where the films were made. Movie makers Warner Brothers plan to offer a tour of the studios from next year.
Some of the jumpers, made by machine from New Zealand lambswool which is then spun into yarn in Dalry, Ayrshire, are now on show at London Film Museum.
Colin bought the company with business partners from KCM Energy, Keith Murray and Mark Davidson, in 2008 after it went into liquidation.
The factory originally started as a charity providing work for ex-servicemen after the Second World War, but became Lochaven in 2003.
The firm also makes other clothing including outdoor wear in its own fabric, Naturefleece.