Forget Fitbit, why not try a real heart rate monitor?

To say that the Fitbit wearable heart rate monitors don’t skip a beat would be an overstatement, according to a lawsuit filed against the smartwatch manufacturer. Specifically, the complaint targets the company’s wrist-based monitors Charge HR ($150) and Surge ($250), both equipped with an LED technology called PurePulse. “Far from ‘counting every beat,’ the PurePulse Trackers do not and cannot consistently and accurately record wearers’ heart rates during the intense physical activity for which Fitbit expressly markets them,” the lawsuit says, making reference to the Fitbit’s slogans such as ‘Every beat counts’ and ‘Know your heart.’

Allegedly, “plaintiffs and many consumers like them have experienced – and testing confirms – that the PurePulse Trackers consistently mis-record heart rates by a very significant margin, particularly during exercise,” leading to inaccurate and dangerously low bpm (beats per minute). For instance, plaintiff Teresa Black of Colorado said her Fitbit Charge HR measured her heart rate at 82 beats per minute while a personal trainer measured it at 160 bpm – a difference of almost 50%. “Plaintiff Black was approaching the maximum recommended heart rate for her age, and if she had continued to rely on her inaccurate PurePulse Tracker, she may well have exceeded it, thereby jeopardizing her health and safety,” the complaint said. Similarly, David Urban of Wisconsin said his Surge device consistently underreported his heart rate by 15-25 bpm as he was exercising and never displayed a reading above 125 bpm, as compared to chest strap-based triathlon monitor readers.

“I'm a mom. I like to work out. I like to be fit,” third plaintiff Kate McLellan of California told Today. “My Fitbit was saying that [my heart rate] was at 114, which is really, really low.” When she contacted Fitbit’s customer service department, the representative “made it sound like it was my fault, like I was using it wrong or wearing it wrong. She said it's not really meant to track your heart rate all of the time. ” But the lawsuit states that “the heart-rate monitoring function of the PurePulse Trackers is a material — indeed, in some cases, vital — feature of the product.” Moreover, it says that a board-certified cardiologist compared the Fitbits’ heart rate measurements with those from an electrocardiogram (ECG), and found that for heart rates above 110 bpm, the Fitbits were off by 25 bpms on average, with some readings wrong by as much as 75 bpm, rendering them “effectively worthless as heart rate monitoring devices.”

Though there are only three plaintiffs, supposedly “scores of customer complaints confirm these are not isolated incidents.” Conversely, many users have defended the fitness trackers, giving them 4 and 5 star reviews on Amazon. Fitbit is no stranger to legal action; Terry Collins of CNET writes that “The company is already in the midst of several suits against rival wearable-device maker Jawbone over accusations of poaching workers and stealing trade secrets. Fitbit issued a recall in 2014 after customers complained of rashes after wearing the devices and a lawsuit over misleading advertising.” Nevertheless, “We do not believe this case has merit. Fitbit stands behind our heart rate technology and strongly disagrees with the statements made in the complaint and plans to vigorously defend the lawsuit. Fitbit is committed to making the best clip and wrist-based activity trackers on the market,” a Fitbit spokesperson said in a statement. “Our team has performed and continues to perform internal studies to validate our products’ performance… But it’s also important to note that Fitbit trackers are designed to provide meaningful data to our users to help them reach their health and fitness goals, and are not intended to be scientific or medical devices.”

Still, lawyer Jonathan Selbin hopes to get refunds – or at least partial refunds for customers who purchased the higher priced devices – for the unsatisfied customers. The moral of the story here is that, as clichéd as it sounds, all that glitters is not gold – and expensive does always equals better. Why, at Discount Medical Supplies you can find wrist watch heart rate monitors for as low as $41.97. And you can believe these cheap medical supplies have not been the object of a lawsuit.

Related: Cardio Disease Prevention:Stop Smoking & Start Breathing!