Apple is giving Facebook and various other companies access to the Apple Watch ahead of its Monday unveil, according to Bloomberg. The report says Facebook, airliner United Continental Holdings Inc. and others have “spent weeks” on Apple’s campus working hard on developing apps for the watch.

Bloomberg says developers have been given special access in a top-secret lab inside of Apple’s headquarters. Whomever enters must sign a non-disclosure agreement and follow extreme guidelines to prevent unknown details to be leaked about the wearable device.

“The companies, sometimes sharing a room, must bring in source code for their apps on a computer hard drive that can’t leave Apple’s headquarters,” Bloomberg writes. Furthermore, Apple is storing the code and will share it closer to the Apple Watch’s availability.

Secrecy shouldn’t surprise anyone. Since it’s first unveiling last September, the company has yet to mention key details such as battery life, upper tier pricing, and band/case interchangeability.