When you buy a new Wear OS smartwatch, you might check the specs for special features or battery life estimates. But now there is a more pressing reason to read the fine print before checking out.

Google has confirmed that its unified Wear OS (formally known as Wear OS 3) is not compatible with smartwatches with Snapdragon Wear 3100 chips or earlier. This older chipset is found in many smartwatches currently on the market, including the Fossil Gen 5 LTE, the Xiaomi Mi Watch, and one of the best running watches, the Suunto 7.

If you want to benefit from Wear OS 3, an improved version of Google's wearable software that integrates Samsung's Tizen and Fitbit's fitness platform, stay away from the Snapdragon Wear 3100 smartwatch.

Instead, a select collection of Wear OS smartwatches will be eligible for Wear OS 3, which will roll out to older devices in 2022; any model with the Snapdragon Wear 4100 will be able to migrate to the new software. Currently, that coverage is limited to Mobvoi's TicWatch Pro 3 and TicWatch E3.

Not many smartwatches may yet be powered by the Snapdragon Wear 4100, but it is expected to be included in future TicWatch devices and in the next generation Fossil collection.

It is safe to assume that smartwatches debuting next year will ship with Wear OS 3 installed. Owners of existing Snapdragon Wear 4100 smartwatches will not be so lucky. Google warns that the update requires a reboot to factory settings, which could hinder the user experience.

In other words, even if you have an eligible smartwatch, you may want to hold off on upgrading to Wear OS 3. The Samsung Galaxy Watch 4 will have Wear OS 3, but the Samsung Galaxy Watch 3 and earlier Galaxy Watch models will be powered by Tizen.

In any case, think twice before purchasing a Snapdragon Wear 3100 smartwatch; there may be Amazon sales and other discounts on these devices as the official rollout of Wear OS 3 approaches.

We will also see a preview of the updated Wear OS on the new Galaxy Watch next month, but it will be layered by Samsung's One UI Watch and run its own Exynos 9110 chipset rather than the Snapdragon 4100 Note that it will be running its own Exynos 9110 chipset, not the Snapdragon 4100.