Using the app "Heart Analyzer" on IOS, here is what I have found:
1) As show in the pic below, the heart rate monitor will ping almost constantly. Which is good. I think the only prohibitive measure is on the receiving end, but more then enough to stay in zone or prevent peaks.
2) The battery is a button battery (C3232) that I did go ahead and change. the seal is there, but I plan on adding a little extra sealant to prevent the battery from getting wet. Just some cheap sealant maker from should do.
3) Connectivity was not bad. You will need to connect bluetooth each time, but not the end of the world.
4) Apple Watch. I am running the Ultra 2 and have it connected directly to it. I have not connected it to the phone and do not carry my phone on runs, hikes, or workouts. When I do get back to my phone, all the data is there. This is a big win for me.
Conclusion: for the money, I think this is a functional little unit. Longevity is still a mystery at this point since I am only a few weeks into using it, but the more expensive alternatives do not seem to hold the value this does.

I can't believe they're now (Nov 2025) selling this for $12.95. I bought it in May 2025 for $21.00 and it has worked flawlessly for 6 months. I decided to give this "cheap" one a try after having to replace my $70 Garmin HRM every 6-9 months because it would either fall apart or stop working. This KYTO one is so much better than the Garmin one. Just make the switch if you're debating it. It's accurate and durable. If I could give this 6 stars, I would!
Edit: I see other reviews complaining about connectivity issues. I've had zero issues in 6 months connecting to my Garmin 820 cycling computer and my Moto G Power phone using the Polar Beat app.

Does not work. Will not recognize the KYTO app.

For the price, this is a pretty decent unit. Not perfect, but at the price, I can't quibble. Things to know:
– BAD: The ANT+ connection is spotty if you have a number of ANT+ signals going. We have 2 trainers, cadence sensors, and heart rate straps all going at once, and things got rough for the HR strap when everything was cranking. That's as much an ANT+ problem as anything. The protocol doesn't manage a lot of traffic or dropped packets well. HOWEVER
– GOOD: The Bluetooth Low Energy (BLE) connection is rock solid. Moving both HR straps to the BLE connection made everyone play nicely.
– BAD: The battery cover is a pain. Most devices have a 1/4 turn cover to hold the battery. This has a flat plate held by 4 annoyingly tiny screws. They screw into the plastic, so be careful not to strip them out.
– GOOD: It comes with a battery already installed (which I wish I had known before wrestling the 4 tiny screws.)
– GOOD: With the electronics able to disconnect from the strap, keeping the strap clean is pretty simple.
– GOOD TO KNOW: The module has the 4 character ID code embossed on the battery cover. If you have 2 devices to pair, as we do, make a note of the code for each, and don't inadvertently swap the battery covers!
– GOOD TO KNOW: Other reviewers mentioned a blinking light to tell you it's active. I couldn't see it, so either it was deleted, or it isn't bright enough to see in our well-lit basement.

WORKS GOOD

Very good monitor, the strap is high quality, comfortable, soft, and keeps its elasticity. The sensor accurately captures my heart rate during exercise and immediately connects to my phone on a massive variety of apps. The build quality of the monitor itself is great, its small, and sleek. Excellent value for money.

Great value strap. Use it with my Polar H10 and H9 chest transmitters, as my Polar strap got too old for use. Works well. Happy with decision to try a cheaper strap.

So far so good , works as well as the original.