The pro rope has extensions than you will ever need, but progression is the key. PU coated rope with printed line lengths, user friendly features, like short 50ft mainlines for beginners, to 2.5ft extensions on the opposite ends so you can progress out as you need. Why tie knots in your pro rope, just make it work for everyone from the start.
Total length with bar 80ft // 50ft, 60ft, 65ft, 70ft, 75ft, 77.5ft. 80ft.