Mammoth Flossy Chews Cottonblend Color 3-Knot Rope Tug, Assorted Colors (XL) $3.49

I love these ropes. I use them for my GSD and they last a decently long time (few months). This is the cheapest ever for the XL. Picked up a few.
https://www.amazon.com/dp/B001GIIZQQ