W'underwear!!

I am desperately searching for two things. One is a W’underwear should guard for my 17+h warmblood. The second is the sizing chart so that I know which size he needs! I can not find it anywhere. I was told that the wonderful woman who invented Wunderwear for horses sadly died of cancer. It seems everything was kinda wiped off the Internet after that.
Does anyone know what size I need? I have a C0-2 and it is almost big enough. Perfect for a 16+ horse.
THANK YOU for any help!