New York ? Is that a flashing “Z” in your pocket, or are you just glad to still have your cell phone?

The Z stands for Zomm, a little multipurpose gadget for your pocket, purse or keychain whose main function is to prevent you from walking off and leaving your phone somewhere. It does so by lighting up and sounding an alarm when it’s more than 30 feet from the device to which you have electronically linked it.

A lot of technology products are irritating by accident. The Zomm — and the Phone Halo, a similar-in-concept but less- versatile competitor — intend to irritate, and by and large do a good job of it.

About 30 million wireless phones go missing every year, according to Asurion Corp., the Nashville, Tenn.-based wireless-phone insurer. Apple, Microsoft and others offer various find-my-phone services and applications that may help you locate a lost phone — if you’ve enrolled your phone ahead of time, and in Apple’s case purchased its MobileMe service. But they don’t do anything to prevent you from losing it in the first place. That’s where Zomm and Phone Halo come in.

The Zomm device, which costs $79.95, is a disc about 1 1/2 inches in diameter. Once you pair it with your phone via Bluetooth, its large central button flashes every five seconds to reassure you it’s still within range. Walk off, and it begins to flash more rapidly, vibrate and emit an alarm that, even buried in the depths of my pocket, was loud enough to command the attention of several colleagues when I deliberately ventured away from my iPhone.

That isn’t all the Zomm does, though. It also incorporates a speakerphone that allows you to answer incoming calls. While I found the sound too fuzzy for regular use, I could see it coming in handy for someone who might otherwise fumble around in a large bag or purse to find a ringing phone. In addition, the flashing Z doubles as a panic button that, when held for 15 seconds, first emits an alarm and then, if not released, dials your local-emergency-services number and plays a recorded message asking that help be sent to the location of your phone.

While the Zomm works with any Bluetooth-enabled phone, the $59.95 Phone Halo, which is about the size of a rubber eraser, so far is limited to users of BlackBerrys and phones using Google’s Android operating system. (IPhone compatibility is in the works, the company says.) Setup is more involved than with the Zomm; you will first have to download and install the appropriate app on your phone, then configure it.

On the other hand, the Phone Halo offers you a host of notification options — not just an audible tone (which I found too faint, though others had no trouble hearing it) but also via e-mail. You can even configure it to tweet a lost-phone message to your Twitter followers, though fear of public humiliation kept me from trying out that one.

As a side benefit, you can use the Phone Halo in reverse, attaching it to other kinds of things you don’t want to misplace — a briefcase, for instance — and using your phone to warn you. Separate them too far, and the Phone Halo app is preprogrammed to play the 1960s song “(There’s) Always Something There to Remind Me.”

Granted, all that beeping, flashing and, in the case of the Phone Halo, cheesy pop can quickly become tiresome; just ask my co-workers. Then again, that’s exactly the point of these devices. And for many people, it’s a small price to pay compared with the agony of separation from their phone.