Tekhelet strings include everything needed to tie tzitzit including both white and tekhelet strings.
Raavad: 2 of 8 strings tekhelet
Rambam: 1 of 8 strings tekhelet
Tosafot: 4 of 8 strings tekhelet
Raavad Short are suitable for tying according to Gra, Chinuch and Raavad methods
Raavad 7 and Rambam 7 are suitable for tying 7 chulyot instead of 13
For Tosafot according to Rav Schachter, please order 2 sets of Raavad