On Thursday, the Associated Press reported that the Interior Department spent that much last year on a work order labeled, simply, “Secretary’s Door.” Absent answers from the Interior Department and the contractor that performed the work, people began to wonder: How could someone spend that much money on a door?

500 for the door 138,500 for higher admission fee to see the door, rangers to guard and protect the door, and for a comprehensive same day maintenance policy to prevent degradation. Not to mention 1st class seats for people to come look at the door 🚪 — Don (@simplelife913) March 8, 2018

The contractor who performed the work, Maryland-based Conquest Solutions LLC, did not pick up the phone when I called. Their website, however, mentioned that the company specializes in “building automation systems.” So I called Nebraska-based Control Services Inc., another company that provides such systems to government customers. They picked up, and a building automation and control specialist named Dave Harrill explained to me how it’s possible to spend $139,000 on a door.

Harrill said the work order was most likely for an electronic security door. “If it’s an office door, more than likely it’s the electronic lock and latch system,” he said. “Those can get very expensive. And then—more than likely for that kind of money—probably some type of biometrics lock; either a fingerprint reader, or they have them where it’s like a hand pad where you lay your hand in it. It takes the print off of your hand for how it unlocks a door. It also could be a retina reader that reads the retina of your eye.” Pressed on whether eyeball security readers actually exist, Harrill was insistent. “It’s real,” he said. “We have installed quite a few.” Most, however, are installed in big corporate insurance company buildings where customer data is located. “It’s Star Wars, it really is,” he said.

A retina reader would be an extreme measure, but Harrill said other types of security systems could add up quickly—especially if they’re being installed in an old building. The Stewart Lee Udall Department of Interior Building, where Zinke’s office is located, was built in 1936. In many cases, electronics and wiring have to be installed in the frame of the door. “To be honest with you, $140,000 is not really that far out of the ballpark if it’s a high-security type deal,” Harrill said. Whatever kind of door Zinke bought, it certainly makes Environmental Protection Agency Scott Pruitt’s $25,000 soundproof phone booth look like a deal.

Update: Zinke’s spokesperson says Zinke was unaware of the door contract, which is for “fiberglass replacement doors” that are expensive to install in a historic building.