This is a brand-new Slice Engineering Mosquito hot end kit for the Prusa MK3+. I'm including the 3D printed parts for convenience. They were printed with PETG (body) and PC (part cooling nozzle). I had this as a backup for my printers but have since sold them and no longer need this. 
Includes:
You may need other screws or hardware to install this. It's been years since I've installed one and I do not recall what I needed to provide/source myself (some screws are re-used from the original assembly). This is very much a DIY project that is not simple, so please consider that and research the steps before purchasing. Due to the nature of this product and its intended use, I will not accept returns. Feel free to reach out with questions prior to purchase and I will do my best to answer them.