If you use your inkjet printer often, a waste ink tank is a really good idea. Higher end / larger printers come with these built in. All others have an absorbent pad to collect waste ink. The printer has a crude counter to determine how much the pad has taken in, and when the printer decides it's full, you are done printing until the printer is convinced it's remedied.
This external waste ink tank is the highest quality and design I've encountered (I have been fitting waste tanks to my printers for 10 years). The installation instructions for my printer (Epson SC-P600) were accurate and detailed. The one thing I don't understand is why there is no USA distributor for these, although shipping from UK was quite reasonable.
I have not used the reset key, nor do I expect to use it for at least a year. I'm assuming it will work fine.