You are looking at the WASHINGTON NATIONALS trim that they wear on their on field pants.
1/2 inch wide RED/NAVY/RED
You will get a little over 3 yards which will cover both legs and then some on a 36 inseam pant.
TRIM ONLY NOT THE PANTS!!
You just need to have your local tailor apply it to your favorite baseball pants.
This is very tough to find and is the same polyester trim the NATIONALS use on these pants with exact color scheme.