Cincinnati Reds star Elly De La Cruz caused a brief delay in his team's game against the Washington Nationals on Wednesday.

De La Cruz drew the umpires’ attention in the second inning of his team's 9-2 win at Nationals Park when he stepped up to the plate with a small device that looked like a knob cover on the bottom of his bat.

Although it was small and didn’t stand out much, it appeared to leave the umpires very confused. They called the league office briefly before eventually asking De La Cruz to take the item off.

After it was inspected, De La Cruz was allowed to put the device back on his bat for his second plate appearance the following inning. According to Bally Sports Cincinnati, the knob was actually a cover for a Blast Motion sensor that can read and track metrics on every swing.

This is nothing new for De La Cruz. As the Cincinnati Enquirer’s Charlie Goldsmith pointed out, he has been batting with the knob cover since he was called up to the Reds last month.

The Blast Motion sensor collects data on a number of things, including swing metrics, impact metrics, ball flight and swing quality. Blast Motion was named the official bat sensor technology of MLB in 2016, though the sensor itself isn’t approved for in-game use in the majors. The minor leagues allow players to use the sensors in live games.

De La Cruz, however, was batting with just his empty sensor cover on his bat, which is allowed.

The brief interaction with the umps didn’t seem to throw De La Cruz off at all. He hit a solo home run in the fifth inning that went 455 feet into the upper deck in right field.

That was his fourth home run this season and his 14th RBI. It put the Reds up 5-1.

De La Cruz has shined since he was called up from the Reds’ Triple-A affiliate in Louisville last month. The 21-year-old hit for the cycle in just his 15th MLB game on June 23, which was the first cycle by a Reds player since 1989 and made him the third-fastest to do so in league history.

De La Cruz entered Wednesday’s game with a .308 batting average. He had four hits in the team's 8-4 win over the Nationals on Tuesday, which made him the first player 21 years old or younger with two four-hit games within his first 25 games in the league since 2001, per ESPN.

De La Cruz and Joey Votto each had three hits in the win Wednesday. They also each scored twice, and the Reds used 16 hits to take what was their seventh win in eight games. They hold a 48-39 record, the best in the NL Central. The Nationals, on the other hand, have now lost three straight to the Reds and sit last in the NL East.