Sales of the Apple Watch have nearly doubled year over year, CEO Tim Cook announced on the company’s earnings call today. So far, Apple has refused to give out exact sales numbers for the Apple Watch, as it does for its iPhone and iPad, and has instead bundled the wearable device into its “other devices” category that includes Beats products, AirPods, Apple TV, and accessory sales.

Frankly, it’s a smart move by Apple. The admission by Cook is likely a response to major companies like Google, Amazon, and eBay removing support for the smartwatch recently. While Google said it expects to support the platform again in the future, Amazon called its participation with the Apple Watch an experiment. Those kinds of third-party issues combined with an inconsistent smartphone market would likely spell volatility for the company’s stock price.

The smallest Fortune 500 company pulled in $5.1 billion in revenue last year

Cook also noted that revenue in the last year from Apple’s wearables — the Apple Watch, Beats headphones, and AirPods — was the size of a Fortune 500 company. Given that the smallest Fortune 500 company pulled in $5.1 billion in revenue last year, Apple has developed a very valuable wearable division. But given the strength of Apple’s headphone offerings — it owns 40 percent of the Bluetooth headphone market and 11 percent of the total headphone market — we’re still far away from being able to parse exactly how robust Apple Watch sales may be.

Unless Apple finally decides to tell us.