The best gift you can give an elderly loved one may be the ability to stay in his or her own home. Medical alert systems promise to help make that possible.

“We're seeing this trend of baby boomers wanting to live more independently, as opposed to moving into an assisted living facility,” says Neil Lakomiak, director of business development and innovation at UL's Building and Life Safety Technologies division. “Many people would rather age in place.”

In a health emergency such as a fall, the user of a medical alert system just pushes a button on the wearable device to summon help. But how do you find the right system with so many products on the market?

UL recently published a buyer's guide that offers a concise list of questions to ask. “We're trying to educate both the aged loved one and the family members who typically make the buying decisions,” says Lakomiak.

If you’re in the market for a medical alert system, aka personal emergency response system or medical emergency response system, here are eight factors to consider.

Related: 4 Tips for Getting Your Loved One to Wear a Medical Alert Pendant

Durability and comfort. Often worn by people with mobility and motor-control issues, the wearable device needs to survive drops, falls and other rough handling. Ask if it can be worn in the shower or around water, and under what circumstances it is water resistant or waterproof, says Lakomiak.

If the device involves a bracelet monitor, inspect it for sharp edges and ask about the material that will be in constant contact with the skin. Some materials could cause irritation. Also ask about its comfort and reliability in local weather conditions, such as a hot and humid climate, says Lakomiak.

Integrity. It should include an alarm that notifies the user if the system is malfunctioning or if the person is out of monitoring range. For instance, if the wearable device is connected to the home's land-line phone, it might not work if the user leaves the house. Keep in mind that if it's a mobile system that does work when the person leaves the house, he or she might not get a signal in an underground garage, according to Lakomiak.

Battery life. The system should notify you when it's time to recharge or change the battery. “The wearable devices typically use a coin cell battery, typically lithium ion,” says Lakomiak. “Some are rechargeable and can last a long time before you have to replace or recharge them.”

Cybersecurity. Find out how well the system is protected against unauthorized access by people who might try to intercept its signals or compromise your data. “For example, if a system performs real-time monitoring of a person's activities, a would-be burglar would know when they're not in the house,” says Lakomiak. (If you don't want it to monitor your loved one all the time, look for a model that has a feature to turn location services on and off.) Hackers also could disrupt its ability to send out alarms, send out false alarms or even turn the device off.

Related: 6 Ways to Protect Yourself from Medical ID Theft

Ease of use. If your loved one wasn't a techie earlier in life, he or she may not want (or be able) to deal with tasks like performing updates. “If it's a mobile device, are regular updates needed?” says Lakomiak. “Is it done automatically, or is there a multi-step process?

In an emergency, the user should be able to summon an ambulance with the touch of a button instead of having to dial 911. “You might be incapacitated and not have the ability to use to your phone,” says Lakomiak.

Movement monitoring. The best devices have this feature, but not all of them do. “If you fall to the ground, some devices can detect this and automatically issue an alarm,” says Lakomiak. Some systems even look at movements or behaviors that predict a future fall or near miss, so that whoever is monitoring it can ask you if you're having mobility problems.

Related: Watching Your Step: Safety Tips for Preventing Falls Among Seniors

Customer service. The device is only as good as the service provider that monitors it, if you’re using one. They should have a well-trained staff, be open around the clock and respond quickly to alarms according to the Federal Trade Commission (FTC).

“The smaller, local companies are providing better customer service than the national companies,” says Bob Harris, president of The Attrition Busters, which helps recurring-revenue businesses with their customer relations issues. Harris' company recently performed a “mystery shopper” survey, contacting medical alert companies while pretending to be existing or prospective customers.

Overall, they found monitoring personnel to be efficient and caring during an emergency. “They have the ability to keep people calm while they're summoning a responder” such as an ambulance, he says.

Fees. The industry's salespeople often use high-pressure sales tactics, sometimes selling a customer a system that doesn't meet his needs, according to Harris.

Before signing a contract, read it carefully. Take note of any installation or cancellation fees or other extra charges.

It's increasingly common to purchase the equipment separately, not from a monitoring service, and have a caregiver monitor it. It's also the least expensive option, as the monitoring service can run from $10 to $30 per month, Lakomiak says.

Medicare, Medicaid and insurance companies don't typically cover the cost of a medical alert system, according to the FTC. However, your local hospital or social service agency might help if you meet income requirements. They also might set you up with a system directly, according to the FTC.

Be wary of telemarketers and spam emails offering a free system. The federal government is currently trying to shut down a massive fraud operation in which salespeople attempt to trick elderly customers into accepting “donated” equipment that includes a hefty monthly service fee.

Related: Protecting Mom or Dad from Financial Abuse

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David Arv Bragi is a freelance journalist and marketing consultant. He has been writing about health and safety issues since the 1990s and currently lives in Portland, Oregon.