I have to admit, although I have built and modified PCs in the past, I was a bit reluctant to do the same in my Mac. But, it was out of warranty and it was filling up, and there's nothing otherwise wrong with it. Despite the advice sprinkled across the internet to avoid doing so, I decided to try replacing the SSD.There is an instruction book in the package which (judged by the normally-dismal standards of Chinese documentation) was not bad (but was still pretty tough to follow - make sure you read it all before starting work). The supplied tools are good quality, and disassembling the machine was easy (though: remember to unplug the battery - it's very easy to miss that instruction!) The module fitted perfectly, and I had no trouble putting everything back together again.I was intending to restore from a Time Machine backup, and the instructions implied that the ssd would have an operating system (or at least an installer) on it. No, it didn't: I had to go through a very long process to download an installer, then download and install an operating system, then do the restore. Counting the few false starts, it took three days (and a lot of download data) to complete.But, having done it, the ssd is working well. It's perfectly fast enough, seems entirely reliable, and I have lots more space to play with.Overall, having done this successfully once, I'd have no hesitation in doing it again on another machine (in fact, I'm going to upgrade my partner's machine the same way). The product does what it says on the tin, and it's good value for money.One word of warning: every model of Mac seems to use a different-shaped connector. Make absolutely certain that you're buying the correct type for your machine. I thought I knew what I was doing, but I still got it wrong first time.