MILWAUKEE -- Brook Lopez strolled from the Fiserv Forum tunnel to the court ahead of a January game, stopped and furrowed his brow in confusion. Something was missing.

Where, he wondered, are our seats?

The plushy seats that are usually set up for Bucks players during home games had been replaced by folding chairs. These folding chairs were nice, sure, but the metal legs and double-stuffed cushions seen along the sidelines of most NBA arenas paled in comparison to the state-of-the-art bench seats Bucks players usually perch on during home games. Their chairs, he later learned, had been taken out temporarily for maintenance.

"I'm so glad to know they're coming back," Lopez said.

This wasn't the type of maintenance you'd expect for bench seats. In a luxurious, brand-new arena that features customized amenities such as shower nozzles mounted 9 feet above the ground to accommodate the league's giants, the seats might be the most thought-out design touch. They're so unique, in fact, that the Bucks spent months ironing out an exclusive business arrangement with the manufacturer.

Made to heat to 106 degrees Fahrenheit -- the optimal heat to maintain muscle temperature, according to one study -- these sleek, matte black seats took three years, 12 University of Colorado students, a New Zealand research group and six prototypes to perfect. At the touch of a button, the seats can be raised to accommodate long-limbed Giannis Antetokounmpo or lowered for Eric Bledsoe's more compact frame. Don't bother asking how much they cost; even the swankiest home goods stores won't be selling these.

"They're definitely great," Khris Middleton said of the Bucks' new secret weapons. "I put my seat all the way to the top. It's not too comfortable to be scrunched all the way up.

"The heat is definitely needed. You see players with heat packs all over their bodies all the time, so to have a chair that heats replaces the heat packs."

"It's a pretty good bonus. You get to warm your buns up. I've never had anything like that before." George Hill

NBA teams have been in a longstanding arms race with various technologies, such as wearables that report biometric measurements and movement trackers, but the Bucks have taken a different approach. They have designed a product that mixes performance and comfort. Now, because the Bucks own the design of the seats, other NBA teams will have to go through them if they want to outfit their arenas with similar chairs.

While the Dallas Mavericks are widely credited as the first team to install cushy, adjustable bench seats in their arena, the Bucks are the only team that gives players the option to toast their hamstrings.

"It's a pretty good bonus. You get to warm your buns up," guard George Hill said. "I've never had anything like that before."

The sideline seat warmers, manufactured by Figueras USA, were conceived by Bucks director of performance Troy Flanagan.

"An over-the-top amount of research and design went into these chairs," Flanagan said. "It is the most carefully engineered seat you could ever imagine."

The quest for the perfect seat began in 2015. Flanagan read a study in the Medicine & Science in Sports & Exercise Journal that noted that British cyclists who wore battery-operated, heated tracksuits between their warm-up periods and their races exerted 9 percent more power output than cyclists who let their muscles cool in between. At first, Flanagan tried to design heated pants for the Bucks, but he quickly concluded that it was unreasonable to ask Middleton to charge his tracksuit before each game.

A year later, the Bucks recruited University of Colorado mechanical engineering professor Jack Zable to help design the first prototype of the chairs. That prototype was flown out to Milwaukee for the players to test and rate its durability, comfort and structure.

"We wanted to make sure that they were safe," Flanagan said. "They are super robust, but if a player was to collide into them, they are soft, padded, safe and low-voltage."

Flanagan also had to ensure that the seats followed the Bucks' ticketing department's strict height regulations. If the seats were able to be adjusted too high, a player such as D.J. Wilson, who likes to raise his seat as high as possible, might block the view of a valued season-ticket holder.

"They use the height design feature a lot," Flanagan said. "The guys complain that they're a little bit stiff when they get up from conventional chairs."

Giannis Antetokounmpo has heat packs on his knees while sitting on the Bucks' bench, but unlike players on other teams, he also can warm up his hamstrings with controls on the chair. Stacy Revere/Getty Images

Guard Sterling Brown classifies himself as an "in the middle" guy -- he doesn't like his seat too high or too low. Brown can take or leave the heat, he said, preferring to apply heat packs directly to his quads. Antetokounmpo and Lopez adjust the seats all the way to the top to allow for extra leg room. Malcolm Brogdon rocks the lowest seat.

"I think Malcolm is the only one who does that. I don't know what his issue is," Wilson joked. "I wouldn't do that."

Now that the Bucks have adjusted to their new seats, they have started to notice inferior products around the league. Former Bucks big man and current Piston Thon Maker insists that Cleveland has the NBA's most uncomfortable seats because the chairs are lower than the court, causing players' knees to crunch up into their chests. When LeBron James played in Cleveland, he and then-head coach Ty Lue would use booster seats to elevate their perches, but the cushions were not available to every player.

The verdict: The adjustable height is imperative. Most players are not convinced, however, that the heat makes a noticeable difference in their performance.

"The seats are great, but not because of the heat -- because they are adjustable," Brogdon said.

At 7 feet tall, Brook Lopez can find his knees approaching chin level on traditional folding chairs at arenas outside of Milwaukee, such as the United Center in Chicago. AP Photo/Nuccio DiNuzzo

Added Wilson: "The heat is just for your backside. I still use the heat packs for my knees."

Word of the seats has spread. Opposing players will pause their warm-up routines to test Milwaukee's seats, raising them up and down, only to be disappointed to find that the visitors bench doesn't have the same features. Within weeks, rival teams began to call general manager Jon Horst about his magical chairs.

Among the teams that have reached out to Horst are the Golden State Warriors, who are exploring options for the team's seating in their new arena.

"There are a number of teams that have taken notice on their own or getting second-hand information from players who've experienced the chairs," Horst said. "We have a number of general managers who have called me and asked about the chairs."

The cutting-edge seats, then, are a bit like the rising organization that designed them. The secret is out.