Tens of thousands of employees at more than 18,000 U.S. hotels will soon carry panic buttons to help protect them from harassment and assault in an era of heightened awareness around the #MeToo movement.

More than a dozen big hotel chains — including Marriott, Hilton, Hyatt, IHG and Wyndham — said Tuesday that they will provide personal safety devices by 2020 to all employees who deal one-on-one with guests. The companies will also train staff to identify and report harassment and publish anti-sexual harassment policies in multiple languages.

The devices will vary by hotel. In a new, Wi-Fi enabled hotel, for example, companies may give out devices that automatically send the employee’s location to security officers. In an older or smaller hotel, they might distribute devices that emit a loud shriek.

The American Hotel and Lodging Association, which is backing the effort, says around three-fourths of its 25,000 member hotels are participating right now. It is working with harassment and human trafficking organizations to develop training and testing devices to help hotels figure out what works best.

This isn’t the first time hotels are giving panic buttons to staff. New York has required them since 2012, after a hotel maid there accused French politician Dominique Strauss-Kahn of sexually assaulting her in his suite. Chicago and Seattle began requiring them more recently.

But increasing public discussion about harassment and the #MeToo movement has given the effort a new sense of urgency. Red Roof Inn, Best Western, AccorHotels, Four Seasons and Caesar’s are other participants in the rare display of unity from a fiercely competitive industry.

“The cultural conversations have changed, and we have gotten smarter,” said Erika Alexander, Marriott’s chief lodging officer for the Americas. Marriott plans to make the devices standard at all of its nearly 5,000 hotels in North America by 2020. Eventually it hopes to expand the devices globally.

Rani Accettola, a housekeeper at the Embassy Suites by Hilton in Seattle’s Pioneer Square, has a safety fob clipped to the front of her uniform at all times. If she presses a button, hotel managers and security are immediately notified of her location. Accettola said the system gives her an added feeling of security, especially when she works late.

“At any moment, help is there if you should need it,” she said.

It’s unclear how often the devices will be used, but harassment of hotel staff is an ongoing issue. In a 2016 survey of 500 housekeepers in Chicago, 49 percent said guests had flashed them, exposed themselves or opened the door naked.

The rollout of the devices will be messy. Hotel companies only manage some of their properties; others are managed by franchisees. Some companies may require franchisees to add the devices; others may not. Properties vary widely, from sprawling 2,500-room resorts to 65-room, cookie-cutter hotels by the highway.

Some hotels have already begun the process. Hyatt mandated electronic safety devices last fall and has already distributed them to 4,500 employees at 120 hotels in the Americas, Hyatt CEO Mark Hoplamazian said. Hyatt has also strongly recommended the devices for franchisees, and expects to expand the program globally, Hoplamazian said.

He said the cost of the devices is easily absorbed by the company. Shrieking alarms — the kind most widely used at Hyatt right now — cost around $25 each. A React mobile device, like the one Accettola wears, retails for $70, but big hotel chains will likely be able to get bulk discounts.

Hoplamazian said there haven’t been many reported usages. In one instance, a guest was acting strangely so a housekeeper summoned help. It turned out there was no threat, but Hoplamazian is glad the system worked.

“While the frequency may not by high, the importance of it is really, really high,” he said.

Wyndham CEO Geoff Ballotti said his company expects to distribute safety devices by the end of next year to 5,000 employees in the 450 U.S. hotels it owns and manages. Hilton CEO Chris Nassetta said “tens of thousands” of staff at 4,500 hotels will get the devices by 2020.

Nassetta said the rollout will take time because training staff members how to respond to the devices is as important as the devices themselves.

“We don’t want to create the appearance of safety without the reality behind it,” he said.