If you have a very old Dropcam sitting unused in a closet somewhere, Nest wants to send you a new one. Over the weekend, the company quietly announced a replacement program for the first two generations of Dropcam, a plan that involves giving owners of those models the newer Dropcam HD free of charge. What's the catch? Nest plans to shut out access to Dropcam's video streaming and cloud recording service for those two models specifically, beginning April 15th. Nest says only that those older models don't work with some of its newer features, hence the replacements.

It's unclear just how many devices the program covers. Before it was snapped up by Google's Nest, Dropcam was a privately held company and did not disclose sales figures. Nest declined to say how many units this program will affect.

The replacement is highly unusual in the world of consumer electronics. Most of the time, when a gadget gets older, you're the one that's supposed to buy a newer model. In this case, it's Nest that's picking up the tab on the Dropcam HD, which normally runs $149.99. The reason why is simple though. Dropcam's cloud recording service is the main reason to get one of its cameras, and its cheapest plan is $9.95 a month, going all the way up to $29.95 a month.

The freebie Dropcam some people are getting as a replacement is not quite the latest model. The Dropcam HD came out in 2012 and was replaced at the top a year later with a $199 Pro model (which is currently our pick as the top home security camera). The extra $50 gets you a wider lens, better optics, and Bluetooth LE. In this case, Dropcam's replacing its first-generation model from early 2010, as well as the Echo, which came out just a few months later and added a microphone.

Update January 26th, 4:44PM PT: to note that Nest is not saying how many units this program includes.