served as Grand Marshal for the Indy 500 at the Indianapolis Motor Speedway on Sunday. The country star, who had the honor of commanding the drivers to report to their cars, was also a special guest of IndyCar rookie, Jimmie Johnson.

Shelton collaborated on the design of the custom helmet Johnson wore during with race, which took place over . The driver's "Helmet of Heroes" design pays homage to military service members, including those related to both him and Shelton.

According to , the helmet paid tribute to Shelton's late dad, who served in the honor guard in Korea just after the Korean War, as well as his late brother was in the Army.

Johnson's grandfathers, one of which served on an aircraft carrier during the Korean War and the other who served in World War II, were also represented on the one-of-a-kind helmet.

"I was raised at points thinking, 'I guess I'm also going in at some point,'" Shelton told . "But there wasn't any call for a guitar player in our military, so..."

. His brother, Richie, died in a car accident in 1990 when the future crooner country star was just 14 years old. When the race was over, the "God's Country" singer remembered his late loved ones on social media.

"What a weekend ... wish my dad was able to see that," Shelton wrote alongside photos from the event including two with the special helmet.

"Thank you, Jimmie, for letting him and my brother have a spot on your helmet," he continued. "Thinking about them extra today along with all the heroes who have served our country."

Though a wreck prevented Johnson from finishing the race, the helmet will go on to serve a greater purpose. Fans have until September 11, 2022 to the helmet by donating at least $48 to the American Legion.

"It's not common for me to give up one of these prize possessions," Johnson told . "Helmets are like your guitar you've played for decades," he said, looking at Shelton. "So, very special to me, but it's all for a great cause."