Chipolo just announced the Chipolo Card for wallets, calling it the "world’s thinnest Bluetooth tracker." A bold claim considering the TrackR Wallet 2.0, announced in January, is 0.15-mm thinner. Not that it really matters since neither device is shipping yet.

For the most part, Bluetooth trackers from companies like Chipolo, TrackR, Tile, and others have become so small that they're pretty much attach-and-forget. Trackers on lost items emit an audible alarm from their on-board speakers when within range (100-200 feet, or less with obstacles) of your iPhone or Android phone. Otherwise, you'll receive a location alert whenever someone in your tracker's network wanders within range of your tagged item. Trackers work really well when attached to keyrings, backpacks, purses, and luggage — just not wallets, because the first batch of thin trackers weren’t all that thin.

The Chipolo Card is just 2.15-mm thick and features a 95-decibel alarm, 12-month battery, and 200-foot range. While thin at 2.15 mm, it's still about the thickness of three credit cards, but it’s quite a bit shorter and narrower. That makes it suitable for most wallets, or any of those hybrid wallet-cases for smartphones, tablets, and Kindles. 

The $29.99 TrackR Wallet 2.0 announced in January measures just 2.00-mm thick, by comparison. However, its range is only 100 feet compared to Chipolo's 200, but TrackR has the advantage of user-replaceable batteries. TrackR was supposed to begin shipping Wallet 2.0 in the spring but the company still shows a preorder status on the store. At this point, we'll have to see who ships first before doling out the world's thinnest title.

The $35 Chipolo Card is up for preorder now with shipments expected by "late September."