I think they're a waste of money and just luring desperate women into spending way more than necessary.
I bought one and hated it by the end... The sticks are £1 each ish. And you can only do one a day. And it recommends you do it in the morning which is the opposite of what all of the other tests say (most recommend late afternoon/early evening), obviously you can choose an afternoon window but it annoys me the instructions say morning.
They also lie to you. As soon as you get one High result, the machine is programmed to keep giving you highs until you get a peak regardless of what the stick actually says. You'll also get a 2nd day of peak after the first regardless of what the stick says. This is all in the instructions but seems a bit disingenuous.
I much much preferred using the internet cheapies twice a day. Then when the lines looked the same confirming a Peak with a clear blue smiley stick. Far far cheaper than the monitor and I think a lot more reliable.
And all the sticks do is compare the two lines electronically which is exactly how all of the other stick work but you look at them rather than have a machine read them.
I genuinely hated that monitor.
We got our bfp a couple of months after I ditched the monitor in favour of internet cheapies.
Best of luck, I know how miserable the ttc months can be. My advice is not to waste your money, or at least spend it on something like acupuncture which is good for the soul as well as conception 