More than a third of people in the United States do not feel safe walking home at night, according to a Gallup poll, which is a good explanation for the recent surge in personal safety wearables coming to the market.

In the past six months, five companies have announced wearables with the capability to send emergency alerts to friends, family, and the police. Some have the feature built in to a more sophisticated device, while others make it the primary functionality.

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Wearsafe is one of the latter, it announced a wearable tag on Wednesday that, once pressed, places select family and friends in a group chat. The chat will receive your GPS location and a 60 second audio file recorded before the button was pressed, which should provide more context to the situation.

Nimb offers similar functionality, but in the form of a ring. Both devices send out an alert through Bluetooth and both require your close connections to phone the emergency services. Roar differs slightly, it also sends out a loud alarm that will supposedly deter attackers.

Roar’s wearable is already available for pre-order and will ship this fall. Nimb launched on Kickstarter, reaching its $50,000 goal in 18 hours and currently sitting at $158,000 with 30 days to go. Wearsafe is using a different method, a $5 per month subscription—the tag comes free.

While a dedicated wearable for personal safety may be useful, we are starting to see this functionality embedded into multi-purpose wearables, which may be good enough for most people.

How long can these single purpose wearables last?

In Pebble’s latest Kickstarter, it announced Core, a clippable device that streams your Spotify music, tracks your fitness, and also has a button that can alert your close connections to an emergency. All of this comes for $20 less than the Nimb, which only provides alerts.

Apple also plans to add emergency alerts to the Watch, Sport, and Edition in the next major update. That’s a more expensive option, but bundles the alert with a huge variety of smartwatch functionality.

Ultimately these single-use devices are on a limited lifespan. Wearables currently don’t provide this functionality, but by next year we expect Android Wear smartwatches and Fitbit trackers to come with an emergency alarm for users, if it becomes a heavily requested feature.