It’s no secret that the market for tablets is declining. The fourth quarter of 2015 saw a 13.7 percent drop in sales over the previous year, but there is a bright spot. Detachable devices are on the rise, however, doubling in sales over last year, according to a new report from the IDC. It’s an area where Apple boasts a strong lead over every brand, including Microsoft. It also appears that Apple’s iPad Pro outsold the Surface Pro in sales.

“One of the biggest reasons why detachables are growing so fast is because end users are seeing those devices as PC replacements,” comments IDC tablet research director Jean Phillippe Bouchard, “We believe Apple sold just over two million iPad Pros [in fourth quarter 2015] while Microsoft sold around 1.6 million Surface devices, a majority of which were Surface Pro and not the more affordable Surface 3. With these results, it’s clear that price is not the most important feature considered when acquiring a detachable – performance is.”

That’s an important distinction, because it digs into the heart of the difference between the current generation of high-powered detachable tablets and the mobile-focused systems losing traction in the marketplace.

Although Amazon’s $50 Fire Tablet appears to be an exception to this rule. Its price point beats out basically every other device on the market, and close integration with Amazon services is a boon for many users.

Microsoft is mostly left out of the conversation. The Surface sales serve as a comparison point for the iPad Pro, which helped lead Apple to a 24.5 percent market share in the end of 2015. Microsoft doesn’t even make the top five in sales, pushed out by Samsung, Amazon, Lenovo and Huawei.

If Redmond wants to make a serious effort at creating a market leading line of detachables, it’s going to be an uphill battle. Even with iOS on the iPad Pro instead of a full-featured desktop OS, the Apple option remains much more popular, and that doesn’t appear to be changing anytime soon.