It looks like you need a MK10-MK11 nozzle. (mk10-mk11 being the thread size) From what I can tell the MP Maker Select Plus is a rebranded Wanhao Duplicator I3 Plus. So when you are looking for parts make sure it says its compatible with either printer.
As for nozzles, if you are planning on printing anything abrasive (carbon fiber, metal composite, glow-in-the-dark) you should upgrade to a hardened steel nozzle. If you are going to be sticking with non-exotic filaments, you can stay with brass. If you are looking to print with a wood filament, you may want to get a nozzle with an opening larger than .04 to reduce the potential for clogs. For brands, I have been very happy with Micro Swiss.
You have a lot of choices on Amazon, just use what I said as a starting point for your search. Let me know if this helps. 🙂