The Dutch footballer who has Europe's best footballers gaming on the go

Footballers all over Europe have been pictured with the latest must-have accessory, a portable gaming console.

And the brains behind it? A professional footballer himself.

Kai Heerings is a defender for Dutch top-flight side Fortuna Sittard, but in his spare time he is building a business empire and counts Lionel Messi and Sergio Aguero and F1 drivers Max Verstappen and Lewis Hamilton among his star-studded customers.

The 29-year-old knows all too well the need to keep entertained for life on the road as a professional footballer and it led him to create the JZ Design Game Case, a robust portable case with an inbuilt gaming monitor, which users can connect with a Playstation or Xbox.

Social media has helped the product's popularity explode. Players such as French World Cup winners Benjamin Mendy and Kylian Mbappe have posted pictures on Instagram using the case in their team hotel, while Verstappen is regularly pictured travelling with the case.

Former Chelsea captain John Terry was the first major footballer to buy one, while the company now has clients in seven Premier League teams, plus customers in MotoGP, basketball, DJs and rappers.

"The first big name was Terry," Heerings tells BBC Sport. "He had got our number from another player and called and wanted eight cases.

"We shipped them out, but they arrived nearly all broken. We instantly made new ones and took them to Chelsea ourselves. John had no hard feelings and was one of the nicest guys we've met. When we arrived at Chelsea they wouldn't let us in at first, so we handed the phone with John on the other end and we were treated like royalty."

Soon after their visit to Chelsea, Manchester City striker Aguero got in touch...

"Aguero called for two custom white Game Cases," said Heerings. "Then last year he called again to order the new model, one for himself and one was for Messi.

"We didn't know if he was joking, but it was really cool seeing the incoming money transfer state L. Messi."

Heerings came up with the idea in 2015 with his brother-in-law and co-owner Jens van Zonneveld as they travelled to a football match.

"It was another boring bus ride of a few hours and we chatted about the upcoming training camp, and that it sucks to bring all the separate bits and pieces for gaming and trying to hook it up to the TV in your hotel room," the Dutchman said.

"On the bus rides or on camp there is a lot of free time to kill. Jens said 'let's put some money together and see where we end up'."

The pair made the first prototype and when Heerings took it to a training camp, his team-mates soon wanted one.

"My room was very crowded that camp," he says. "With the guys knowing players in other teams and with them joining other teams, the word spread quickly.

"We received a lot of requests so we had to turn it into a legitimate business."

He adds: "My team-mates are very proud of what I'm doing. If there's a new player who comes to the club and I tell them that I'm the owner of JZ Game Case they always go crazy - they have all seen it on Instagram."

The cases are now made in a factory in the Netherlands, but Heerings and Van Zonneveld like to do the "final quality control" before it is shipped.

The company now has a relationship with EA Sports, who order custom Game Cases for specific game releases and events like last summer's World Cup, while Instagram has been key to growing the hype.

"A few players of the French national team got one last summer," says Heerings. "Our clients come from a wide variety sports and public professions. But most of our clients are international football players from all over Europe."

Red Bull driver Verstappen is a keen gamer and bought one of the cases himself and even gives feedback.

"Because Max plays and travels a lot he is an excellent source for us to hear how he experiences the Game Case on the road," he adds.

Heerings, who started his career at Ajax's academy, says football is still his "number one priority".

"As a footballer we have a lot of free time after training," he says. "We try to manage all meetings beside my job and Jens' job. It's not easy to plan things, because we have training almost every day and a game at the weekend. But for now everything is working very well.

"I'm very focused on being a professional player. But at my age, you need to start thinking about the future. We'll see where the company stands when I end my career as a player.

"For now I can focus on my football career because my brother-in-law and my wife do a lot of the work. I hope that one day it will run smoothly together and that I can say goodbye to football in the right way and focus on the business."

He added: "It was not my main goal [to run a business], It happened by accident, but now I'm very proud of being a company owner for a very cool and innovative product."