At long last, I wrapped the slate-colored device around my wrist.

The rubbery strap was tricky to clasp. I’d already read reviews online complaining about its tendency to come loose, but after a few seconds, I had it secured.

It was a little tight. I loosened it.

Even with the better fit, why did I suddenly feel like I’d handcuffed myself? Wasn’t this what I wanted? Prowling stores for the best price with Web searches, deciding instead to go brick-and-mortar on a shopping quest, racing to a Target to grab the last one.

And now I had doubts? What was I committing to, exactly?

The device is a $130 gadget, a fitness device called a Fitbit Force. Starting this month, it’s become a part of my body.

At the Consumer Electronics Show in Las Vegas, an annual event that took place earlier this month, tech product makers try to set the tone for the year’s must-have gadgets (never mind that Apple does not attend). There, wrist-worn fitness trackers were red-hot.

Devices from companies including Nike, Fitbit and Jawbone already dominate the market. But that’s not stopping Sony, Garmin, Razer and many others from trying to get into the act with dozens of products with names like “Vivofit” and “Misfit Shine.”

Every year at the show, a few categories of emerging products catch fire. In the past, it’s been tablets, HDTV sets and 3-D television (remember that fad?). For 2014, tech companies are pushing higher-res, smarter TV sets, connected auto gear and home appliances — even the humble CrockPot — that connect to the Internet.

But the wristbands are worth considering on their own as part of a larger wave of so-called “Wearables,” electronics meant to be on your body all the time. This category includes smart watches; the idea is that you’ll want the kind of technology that’s on your smartphone, complete with a screen and Internet connection, on your wrist all the time.

Smart watches haven’t really caught on, but the fitness activity trackers, simpler devices that let wirelessly connected smartphones or computers do most of the data heavy lifting, have started to become mainstream. Some models disappeared from store shelves before and after the holidays, shifting cleverly from good gift idea to New Year’s resolution must-have.

I know because shortly before and long after Christmas, I tried to find a Fitbit Force, a newer, well-reviewed version of the kind of activity-and-sleep trackers that Fitbit has been making for a few years.

It was sold out online. It was sold out in stores. When I found one available at a local Target, I rushed over.

You know what they say about being careful what you wish for?

Now that I had the Fitbit, charged and synced to my phone, I began to realize what I was getting myself into.

Living with a smartphone, for those of us who fully commit, is agreeing to take on a life partner. You trust it with your contacts, your appointments, your personal photos and videos, your music, games and phone calls.

But you probably don’t have it on you every hour of the day. It might lay muted next to you at night, but you don’t sleep with it.

The Fitbit I’m using is a constant companion. It tracks sleep, so it’s on even then. The only time it leaves my wrist is when I take a shower and that’s only because it’s not waterproof.

I want the data. I’d like to know how many steps I took in a day and how many calories I burned. I’d love to be able to look back six months and see if my activity was greater than it is now and try to figure out what that is.

But I’m also a little uncomfortable with being tracked all the time even when I’m in on the surveillance and the target is myself.

There are all kinds of worry you could have about where that data goes — who has access to it, who could steal or sell it or what sneaky marketing could be done to push products at you based on your private habits and preferences.

But at a more personal level, I worry that I’m stepping into a zone where what I put out there about myself is becoming more and more involuntary. I actively control what emails I send, what Tweets I post, when I’m visible online for a Google Talk chat.

The Fitbit, however, adds another layer of information about me that I’ll forget is even there, an ever-growing pile of information that is probably useful to someone in some way. Will it be useful to me?

I squeeze the tiny button on its side to scroll through the things it knows about me, what it wants to tell me about my day. Time, steps walked, distance in miles, calories burned, stairs climbed, amount of active time.

I’m not sure what any of that information means, really. So I take more steps and try to find a set of stairs to climb so I won’t disappoint the quiet trainer on my wrist.

Then, I begin to feel a little sorry for this humble-looking wristband of plastic, silicon and glass. I’m expecting an awful lot for $130.

I want it to motivate me to be more active, to exercise more and, eventually, to lose a little weight. I want it to help me sleep better. It wouldn’t hurt if it helped me keep track of what I’m eating and drinking.

With more exercise and better sleep, I’ll be able to write more productively, to more patiently parent my kids, to be a kinder, better person.

Is that crazy, like expecting this thing to lead me to a pot full of gold coins? Isn’t it enough that the device cares enough to pay attention to my boring daily habits without complaint?

Fitness wristbands very likely help a lot of people get hold of their habits, helping them see what they’re not doing enough of and creating an awareness that, in the best-case scenario, fosters change.

But I suspect these wristbands, some of which chime and flash lights and send email alerts, are just as much about our need to be told, at every-increasing frequency, that we’re on the right track. A positive-reinforcement nanny state. But stylish and fun to wear.

Eventually, smartphones, smart watches, activity trackers and whatever technology comes out of the freaky-deaky Google Glass project will merge in some way. Ideally, this digital uber-companion of the future will do a better job staying out of the way, getting your attention a lot less often.

For the time being, the purest expression of wearable tech is the fitness wristband, which can do a lot by just being there, always counting, never judging.

OK, fine, maybe just a little bit of judging. I haven’t hit my stairs goal today. Up the steps I climb.