Sorry I missed that part. They are called Fret Wraps. You can probably find non-name brand ones cheaper, but here's an Amazon link: https://www.amazon.com/Gruv-Gear-FW-1PK-LG-FretWraps-String/dp/B00Y0N18EK/ref=sr_1_3?keywords=fret+wraps&qid=1566866079&s=gateway&sr=8-3
Maybe it's the additional string buzz that can be muted with a fretwrap? My reaper is coming in the mail tomorrow, but in advance I bought this because I know I'll be accidentally knocking other strings and have heard these help. Also a cut-off sock will probably do the same trick haha