... is a mouse. The Wheel Mouse Optical 1.1A USB Wired. I've been using these for a couple of decades now, and I can really recommend them. I've only ever had one fail.
And, of course, they don't make them any more. It seems to be a rule. When a company makes something really good, they replace it with something. Maybe the current crop of Microsoft mice are just as good, but I'd have to wait a few years to know.
So when I spotted a nest of nine of them in an eBay advert (the picture showed ten), I snapped them up.
While I'm on the subject of input devices - I'm still using the IBM "buckling spring" keyboards that were made in 1983, 36 years ago. There are people reading this blog that weren't born when these keyboards were made. What I like about them, is the feel, and the way that you know when you hit a key, because of the buckling spring system they use. I'm glad to say, I bought six of them 20 years ago, when it was still possible to get them.
You can still get keyboards like them (but without the IBM brand) for about £100.