In fact our compatibles are made back to the same specs as the genuine cartridges. This is so quality cant be compromised. In saying this, I don't always recommend compatible cartridges. A lot of the time when a new printer is released. there wont be compatible cartridges available. Even though you might be able to find them on the internet, the quality doesn't seem to stand up due to a lack of testing.
I would also suggest sticking to the genuine cartridges if you are printing in high quality. For other everyday printing, compatibles are a great alternative and you can save quite a few dollars in the process.
Depending on the product, sometimes we supply more compatibles than genuine cartridges. This is the case for many HP and Brother cartridges however brands like Xerox and Samsung we usually supply more genuine cartridges.
In this day and age, the compatibles are brilliant. But we do come across every now and then the client who tried a compatible 10 years ago and vow never to go back because they received a dodgy cartridge. In fact, our fault rate with compatible toners is less than 1%. Which is exactly the same as the genuine fault rate.