NEW YORK (AP) — In a move that ends a tradition dating more than 150 years, Major League Baseball approved the use of an electronic device for catchers to signal pitches in an effort to eliminate sign stealing and speed games.

Since the beginning of baseball in the 19th century, catchers had used their fingers to signal the type of pitch and its intended location.

Chris Zagorski, vice president of replay operations and technology at Major League Baseball, watches Spring Training games on screens inside the replay room at MLB headquarters, Tuesday, April 5, 2022 in New York. In an effort to eliminate sign stealing, Major League Baseball says catchers may use a new electronic signal system to call pitches this season. (AP Photo/Ron Blum)

As video at ballparks increased in the 21st century, so did sign stealing — and worries about how teams were trying to swipe signals. The Houston Astros were penalized for using a camera and banging a trash can to alert their batters to pitch types during their run to the 2017 World Series title.

“It basically eliminates all need to create a sign system, for a catcher giving signs,” MLB chief operations and strategy officer Chris Marinak said Tuesday. “You literally just press a button and it delivers the pitch call to the pitcher. And what we’ve seen so far, it really improves the pace of the game.”

Some teams tried the system in spring training, with manager Tony La Russa of the Chicago White Sox and Aaron Boone of the New York Yankees among those saying they liked what they saw.

Yankees catcher Kyle Higashioka used it a couple of times this spring training, including Tuesday with pitcher Michael King against Detroit in New York’s final exhibition game.

“There’s still some stuff we’ve got to work through, but I mean the fail-safe is to always just give signs. So, that’s always there when we need it. We’re just working out all the kinks right now. If we run into stumbling blocks in-game, we can always give signs. I’m not too worried about it being confusing,” he said.

“I like it. At first today I gave signs to King because I didn’t have a chance to talk to him about it, so I started getting all messed up with it. So I just decided to give signs, and that worked fine,” he said.

MLB is providing each team with three transmitters, 10 receivers and a charging case for the PitchCom Pitcher Catcher Communication Device. It is available in English and Spanish.

“A maximum of five receivers and one transmitter may be in any use at any given time,” MLB wrote in a five-page memorandum Tuesday to general managers, assistant GMs, managers and equipment managers, a copy of which was obtained by The Associated Press.

The electronic pitch-calling system approved by Major League Baseball, sits on display, Tuesday, April 5, 2022 in New York. In an effort to eliminate sign stealing, Major League Baseball says catchers may use a new electronic signal system to call pitches this season. (AP Photo/Ron Blum)

A catcher has nine choices on his wristband device: “four-seam high inside, curve hi middle, slider hi outside, change mid inside, sinker middle, cutter mid out, splitter low inside, knuckle lo middle, two-seam low outside.”

A thin band tucked inside a cap allows the audio to be heard at an adjustable level, envisioned to be used by pitchers, second basemen, shortstops and center fielders.

“When changing pitchers, the manager shall provide a receiver to the replacement pitcher,” the memo said.

Receivers and transmitters can be used only on the field and may not be operated during games in clubhouses, dugouts or bullpens.

“Signals communicated via PitchCom may only be given by the catcher in the game. Signals may not be sent from the dugout, bullpen, a different player in the field, or anywhere else,” the memo said. “Clubs are responsible for their PitchCom devices. Any club that loses a transmitter or receiver will be charged a replacement fee of $5,000 per unit.”

Marinak said about half of the 30 MLB clubs had expressed interest.

Kansas City Royals catcher Cam Gallagher wears a wrist-worn device used to call pitches as he prepares to bat during the sixth inning of a spring training baseball game against the Seattle Mariners, Tuesday, March 29, 2022, in Peoria, Ariz. The MLB is experimenting with the PitchCom system where the catcher enters information on a wrist band with nine buttons which is transmitted to the pitcher to call a pitch. (AP Photo/Charlie Riedel)

“I’m not sure that every team will use it,” Marinak said during MLB’s third annual innovation and fan engagement showcase. “I think this is a kind of a personal preference kind of thing.”

Union head Tony Clark pointed out the devices are not mandatory.

“It was important to ensure the flexibility for players to use — or not use — the technology at their own discretion,” the former All-Star first baseman said in a statement. “The guys on the field are in the best position to make decisions as individuals about whether it’s right for them.”

Players may no longer watch in-game video replays on clubhouse televisions but may review video only on iPads controlled by the MLB office. The video will be updated only at the end of each half-inning and players can go back and replay, but may not see content during a half-inning in progress.

“Players don’t have access to any technology that’s above and beyond what we’re offering in terms of in-game video,” Marinak said. “We also monitor all the transmission of traffic so that we understand what content is being delivered to the iPad.”

The new system of umpires having microphones to explain video reviews to fans began with an exhibition game at Dodger Stadium on Monday night. MLB also is now taking in video from 104 of 120 minor league ballparks

The automated ball/strike system of computer plate umpires will be used at 10 Triple-A West parks, Charlotte in Triple-A East and Low-A Southeast. MLB intends to illustrate the calls on stadium scoreboards.

Seattle Mariners catcher Tom Murphy wears a wrist-worn device used to call pitches as he catches a ball during the sixth inning of a spring training baseball game against the Kansas City Royals, Tuesday, March 29, 2022, in Peoria, Ariz. The MLB is experimenting with the PitchCom system where the catcher enters information on a wrist band with nine buttons which is transmitted to the pitcher to call a pitch. (AP Photo/Charlie Riedel)

Pitch clocks will be used at all minor league stadiums, likely a prelude to their installation at big league ballparks for 2023.

MLB showed off its new 1,400-square foot replay operations center in midtown Manhattan, which opened just as COVID-19 struck in 2020 and replaced a 900-square foot facility in SoHo that had been used since 2014.

There are 90 46-inch professional monitors and 60 24-inch touchscreen monitors in the 31 x 29-foot room, with three desks with six screens behind them for supervisors and administrators, then two more rows with technicians.

MLB takes in 18 cameras from each ballpark showing 60 frames per second plus up to four high-speed cameras as fast as 360-480 frames per second, according to Chris Zagorski, vice president of replay operations and technology.

There is a backup replay center in San Francisco, in case of a power outage in New York. For special event games such as in Dyersville, Iowa, Williamsport, Pennsylvania, and London, a replay room is set up on-site.

Marinak said that fans using the MLB Ballpark app to enter stadiums with electronic tickets rose from 3% in 2017 to 19% in 2019 to 56% in 2021.

MLB also said the earliest helmet advertisements would begin appearing would be during the 2022 postseason. Players agreed last month to uniform and helmet ads, and the jersey ads will not start until 2023 at the earliest.