They're made by POWERPRO
Lots of brands of "braid" fishing lines have useful colors for our purpose. If your grass turns brown in summer, you might consider bright blue or bright red instead of yellow. I've used PowerPro for at least 10 years, but not yet for flying. I hear through the grapevine that synthetic lines will be legal for PA contest use, but IDK the details of what or how big.
What I did find out was that currently 40 lb test is legal, but I think only for engines .25 & under. May well have changed, tho. PW says that he's been flying on Spectra lines and really liked them, but that's all I know about it. Somebody on the CL Contest Board should be able to bring us up to date on this topic.
I'd recommend you be careful where you order from, as I've read about counterfeits being available online from eBay and perhaps others...says Spectra, but isn't. Tackle Warehouse is where I get 99% of my fishing tackle, and recommend them highly, partly because they have an excellent website and partly because they give great service and stock crazy amounts of stuff.
https://www.tacklewarehouse.com/fishingline.html Steve