NEW YORK -- On Pete Alonso’s right cleat was an image of first responders raising an American flag amidst the rubble at Ground Zero. Around it were the red and white stripes of the flag, plus the names of New York City service agencies on site on Sept. 11, 2001 -- the NYPD, the FDNY and so many others.

On Alonso’s left cleat was a silhouette of the New York City skyline as it looked on the morning of Sept. 11, 2001, with the World Trade Center standing proud. That shoe was blue with white stars, and the inscription read: “September 11, 2001.”

• Mets still doing their part to honor fallen hero

Around the Mets’ clubhouse, Alonso’s teammates arrived on Wednesday to find similar shoes in their lockers. Alonso, a rookie, had spent weeks going around the room, writing down shoe sizes and preferred brands. He spent his own money to purchase a pair of cleats for everyone to honor fallen first responders and their families on the 18th anniversary of the terrorist attacks on Lower Manhattan.

“It just came from a place where I wanted to show support not just for the victims, but the families as well,” Alonso said. “No one really knows how deep those emotional scars can be. Living here, just kind of interacting with everybody, I’ve tried to immerse myself in the New York living. I see traces of it every single day, little bits and pieces of it. I just wanted to show recognition to all the people who are heroes -- just ordinary people who felt a sense of urgency and an admirable call of duty. This is for all those people that lost their lives, and all those people who did so much to help.”

Originally, Alonso’s hope was that the Mets could wear the hats of service agencies during their Sept. 11 game against the D-backs, as the team did on Sept. 21, 2001, during the first game in New York City following the terrorist attacks. Major League Baseball preferred that the Mets wear those caps during batting practice, so Alonso pivoted to the idea of creating custom cleats for his teammates.

Working with his agency, Alonso approved the design and constructed a list of teammates’ shoe sizes and brands. The final step was to seek the approval of a few veterans in the clubhouse, who OK'd the idea.

“He had a quick meeting about it and said, ‘This is from me,’” Todd Frazier said. “He’s a fantastic young man and he comes from a great upbringing.”

Alonso was only 6 years old on Sept. 11, 2001. His clearest memories are of his school letting out early, and his parents -- typically an easygoing couple -- being distraught.

This past year, playing in New York, Alonso has gained a deeper appreciation for those affected by the attacks. When he won the Home Run Derby in July, Alonso gave a portion of his $1 million prize to Tunnel to Towers, a Staten Island-based foundation that aids the family members of fallen first responders. He met several servicemen and women during the Mets’ remembrance ceremonies on Wednesday, which he considered touching.

“It’s not just the victims,” Alonso said. “It’s the scars left behind, like someone missing their mom or missing their dad. I can’t imagine what that’s like. The toll isn’t necessarily all taken on that day. It’s progressively after, because there’s not someone there in their family. It’s different from then on.”

As for the shoes, Alonso considers them gifts to each of his teammates -- the least he can do at the tail end of a season that “has been an absolute fantasy.” The Mets can do what they like with them. Alonso, following a 9-0 win over the D-backs, may look for an opportunity to wear his again.

“I just want to give back,” Alonso said. “I want to help. I don’t just want to be known as a good baseball player. I want to be known as a good person, too. I just want to recognize really what this day is about. I don’t want it to be like a holiday. I want it to be a day of remembrance.”