It's advertised to work with Windows and Mac. I have Linux and I like to use it directly on my phone. Didn't know if it would work but just took the chance. Both work!! I use the program divelog Subsurface (others might work too) for it and that works on computer as well as directly on my phone. For the phone I just needed to use an adapter to make USB into USB C (which fits in my phone).So that's great, works very easy! Just don't forget to put your dive computer in the correct menu! For the Leonardo, I had to put it in the last menu (press the big button short presses till you're on the last menu), then it can be read out, otherwise it doesn't let itself be read and then it looks like it's not working.Hope this helps you guysAfter several failed attempts to install the software, I dug a little deeper and found this on the Cressi site:"The interface (optional) uses IR to connect to the diving computer and a USB cable for PC connection. Available for Windows XP - VISTA -7 - 8Mac from OS 10.9 to OS 10.10Please note: Cressi Leonardo and Giotto interface will not work with any most recent software update."My Mac OS is 12.2.1, so I can't use the interface and I'll be returning it. They should be more upfront about that, in my opinion.I was surprised how simple this interface is to use. I wish the software was a little better but this device rocks!I bought this product from Amazon marketplace. It arrived and initially I tried using a Macintosh -- downloaded the latest SW from Cressi. I tried to use it with a Giotto and also with a Leonardo. Did not work at all with either. Downloaded the Windows SW and tried again with both the Leonardo and the Giotto using Windows 7. Still no success. After weeks of googling and fooling around I found a brick/mortar shop in Maryland that gave me the phone number of a gentleman at Cressi USA. We talked and emailed eventually he reached back to the Cressi team in Italy. Took months, but finally the manufacturer shipped me a new unit at no cost. This one worked immediately. It was very frustrating and time consuming, but once I got a functioning device, it is very easy to use and works great. The Leonardo and Giotto are great, and I guess this interface device is too --when you get one that works. The documentation is terrible - does not even say that it is an IR link, or where the IR window is on the device -- probably does not need a lot of documentation if it's working 'cause it is simple and straightforward to use.Device worked perfectly to download Cressi Leonardo dive dataTook a while to figure out how to use it to sync my computer, but once I figured it out, it was fine. It was quite the inconvenience that it's not automatically sold with the computer since there's no other way to download the data. It wasn't until after several enquiries that I even realised I needed this device. Nevertheless, it does the jobThis items was scratched up with a scotch taped on the box. Was definitely not new. Plugged it in and the light came on, so hopefully it works. I've already returned a new Cressi Leonardo Dive Watch from this place and it did not even turn on when I got it. They refunded it right away and I bought a working watch from another Amazon vendor. I'm leaving on my dive trip and can't get another one before I leave so I will keep my fingers crossed when I download my dives.Hands down the best products for freediving or scuba. It's for pairing with the Cressi Leonardo Dive computer watch. If they had a 10 star choice I'd click that. I highly highly recommende both these products. I spearfish from 20ft all the way to 125-130ft. It checks the oxygen toxicity in my blood as well as my set down time's. Plus sooo much more.I was a little nervous after seeing many people complain how difficult this was to get working. I bought this to download the dive information on my Cressi Leonardo computer as I'm interested in learning more about my dive stats as I get more in to scuba diving. I installed the software (downloaded from the Cressi website) on my Windows 10 system, plugged the adapter in and connected my watch and it recognised it and downloaded the dive information on the first attempt. I also tried it with the Divemate app on my android phone using a USB C adapter and again, that worked first time.Whilst the Cressi software isn't the greatest, there seem to be a few alternative options such as Divemate on Android, and a free open source application called Subsurface which I also tested on Windows 10 and that worked fine.Doesn't come with instructions. I went to youtube to figure out how to connect it and download the dives to my PC. You have to go to cressi.com and download the interface software. Once you've installed it, connect the interface to your PC and it will automatically download and install the latest drivers for it. (A PC restart may be required after installation). Then you can open the interface software, open the dive computer's PC Link page and connect it to the interface. The both lights should illuminate on the interface which means it's all working.Supplied cable didn't work - I had to borrow one from my GoPro to make it work.Software is dreadful - it's like how software was 15+ years ago. Software doesn't work on tablet's. Possibly not on Mac's either (see https://www.cressi.com/software)If you want to keep an electronic logbook, 3rd party software is much better (I use Divemate on Android, which is pretty good). You can use this device with Divemate (if you buy an OTG adaptor), but it's bulky if you take it travelling. I suspect Divemate's own IR interface is better (it certainly looks smaller (so more portable) and works with lots of other computer brands - so when you throw away your Cressi computer (which you will), you haven't wasted your money on the interface too).If you don't already own a Cressi computer, steer clear of this interface and Cressi computers in general - they are rubbish.I bought this piece of kit because it advertised that it would work with Macs and guess what - it doesn't!! The software is out of date so I'll just have to wait until there is an upgrade before I can properly rate this interface.Works bit only after a bit of hassle. Had to "disable driver signature" in order for the pc to recognise the driver for the USB (windows 8.1). Only learned to do this from searching various forms.