Four years ago, the big cheese at the house of mouse unveiled a $1 billion plan for streamlining the guest experience at Walt Disney World Resort in Florida. The company would introduce some revolutionary wearable tech called “MagicBands.”

The electronic bracelets would be proverbial “keys to the kingdom” for millions of visitors, allowing them to do everything from pay for meals to access their hotel rooms, just by holding their wrist up to a scanner. It was an ambitious goal, and Disney had its work cut out.

“You’re talking about installing 30 million square feet of of WiFi coverage,” says Austin Carr, who wrote about the overhaul for Fast Company. “You’re talking about installing upgrades to the hotel door locks —about 28,000 of them.”

The project was an enormous undertaking, and required the 40 square mile park to cram state-of-the-art tech into 40-year-old structures. The rollout of the bands, which started out slowly in 2013, wasn’t without its bumps.

“When you entered the park, a lot of guests complained that it wouldn’t read their MagicBands right,” Carr says. “A lot of people had difficulty understanding how the system worked.”

That forced Disney to hire more guest services representatives to handle the complaints. Despite the costs and challenges, Carr says CEO Bob Iger’s risk paid off.

“Just being able to swipe your wrist is a reflection of the world I’d like to see,” he says.

The Internet of Things the MagicBand can do

• Check-in with Disney Magical Express transportation

• Park admission

• Hotel check-in and unlocking Disney hotel room doors

• FastPass+ check-in for attractions and entertainment

• Access special event tickets

• Connect Disney PhotoPass images to account

• Charge food and merchandise purchases to Disney hotel room

• Signal arrival to specific park restaurants, and locate your table using radio frequency (via Wired)